diff --git a/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/OpenAiChatModel.java b/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/OpenAiChatModel.java
index 246b7893c4a..85b06a5a4d6 100644
--- a/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/OpenAiChatModel.java
+++ b/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/OpenAiChatModel.java
@@ -319,7 +319,8 @@ public Flux<ChatResponse> internalStream(Prompt prompt, ChatResponse previousCha
 									"index", choice.index() != null ? choice.index() : 0,
 									"finishReason", getFinishReasonJson(choice.finishReason()),
 									"refusal", StringUtils.hasText(choice.message().refusal()) ? choice.message().refusal() : "",
-									"annotations", choice.message().annotations() != null ? choice.message().annotations() : List.of());
+									"annotations", choice.message().annotations() != null ? choice.message().annotations() : List.of(),
+									"reasoningContent", choice.message().reasoningContent() != null ? choice.message().reasoningContent() : "");
 							return buildGeneration(choice, metadata, request);
 						}).toList();
 						// @formatter:on
@@ -606,7 +607,7 @@ else if (message.getMessageType() == MessageType.ASSISTANT) {
 
 				}
 				return List.of(new ChatCompletionMessage(assistantMessage.getText(),
-						ChatCompletionMessage.Role.ASSISTANT, null, null, toolCalls, null, audioOutput, null));
+						ChatCompletionMessage.Role.ASSISTANT, null, null, toolCalls, null, audioOutput, null, null));
 			}
 			else if (message.getMessageType() == MessageType.TOOL) {
 				ToolResponseMessage toolMessage = (ToolResponseMessage) message;
@@ -616,7 +617,7 @@ else if (message.getMessageType() == MessageType.TOOL) {
 				return toolMessage.getResponses()
 					.stream()
 					.map(tr -> new ChatCompletionMessage(tr.responseData(), ChatCompletionMessage.Role.TOOL, tr.name(),
-							tr.id(), null, null, null, null))
+							tr.id(), null, null, null, null, null))
 					.toList();
 			}
 			else {
diff --git a/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/OpenAiChatOptions.java b/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/OpenAiChatOptions.java
index 14b5ba42536..c7c2159d988 100644
--- a/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/OpenAiChatOptions.java
+++ b/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/OpenAiChatOptions.java
@@ -137,7 +137,7 @@ public class OpenAiChatOptions implements ToolCallingChatOptions {
 	 * modalities: ["audio"]
 	 * Note: that the audio modality is only available for the gpt-4o-audio-preview model
 	 * and is not supported for streaming completions.
-
+	 *
 	 */
 	private @JsonProperty("audio") AudioParameters outputAudio;
 
@@ -264,6 +264,8 @@ public class OpenAiChatOptions implements ToolCallingChatOptions {
 	@JsonIgnore
 	private Map<String, Object> toolContext = new HashMap<>();
 
+	private @JsonProperty("extra_body") Map<String, Object> extraBody;
+
 	// @formatter:on
 
 	public static Builder builder() {
@@ -306,6 +308,7 @@ public static OpenAiChatOptions fromOptions(OpenAiChatOptions fromOptions) {
 			.webSearchOptions(fromOptions.getWebSearchOptions())
 			.verbosity(fromOptions.getVerbosity())
 			.serviceTier(fromOptions.getServiceTier())
+			.extraBody(fromOptions.getExtraBody())
 			.build();
 	}
 
@@ -502,6 +505,14 @@ public void setParallelToolCalls(Boolean parallelToolCalls) {
 		this.parallelToolCalls = parallelToolCalls;
 	}
 
+	public Map<String, Object> getExtraBody() {
+		return this.extraBody;
+	}
+
+	public void setExtraBody(Map<String, Object> extraBody) {
+		this.extraBody = extraBody;
+	}
+
 	@Override
 	@JsonIgnore
 	public List<ToolCallback> getToolCallbacks() {
@@ -630,7 +641,8 @@ public int hashCode() {
 				this.streamOptions, this.seed, this.stop, this.temperature, this.topP, this.tools, this.toolChoice,
 				this.user, this.parallelToolCalls, this.toolCallbacks, this.toolNames, this.httpHeaders,
 				this.internalToolExecutionEnabled, this.toolContext, this.outputModalities, this.outputAudio,
-				this.store, this.metadata, this.reasoningEffort, this.webSearchOptions, this.serviceTier);
+				this.store, this.metadata, this.reasoningEffort, this.webSearchOptions, this.serviceTier,
+				this.extraBody);
 	}
 
 	@Override
@@ -665,7 +677,8 @@ public boolean equals(Object o) {
 				&& Objects.equals(this.reasoningEffort, other.reasoningEffort)
 				&& Objects.equals(this.webSearchOptions, other.webSearchOptions)
 				&& Objects.equals(this.verbosity, other.verbosity)
-				&& Objects.equals(this.serviceTier, other.serviceTier);
+				&& Objects.equals(this.serviceTier, other.serviceTier)
+				&& Objects.equals(this.extraBody, other.extraBody);
 	}
 
 	@Override
@@ -933,6 +946,11 @@ public Builder serviceTier(OpenAiApi.ServiceTier serviceTier) {
 			return this;
 		}
 
+		public Builder extraBody(Map<String, Object> extraBody) {
+			this.options.extraBody = extraBody;
+			return this;
+		}
+
 		public OpenAiChatOptions build() {
 			return this.options;
 		}
diff --git a/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiApi.java b/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiApi.java
index f7e72246e97..2a58a79c2ef 100644
--- a/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiApi.java
+++ b/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiApi.java
@@ -29,7 +29,10 @@
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.annotation.JsonInclude.Include;
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.node.ObjectNode;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
@@ -187,6 +190,7 @@ public ResponseEntity<ChatCompletion> chatCompletionEntity(ChatCompletionRequest
 		Assert.isTrue(!chatRequest.stream(), "Request must set the stream property to false.");
 		Assert.notNull(additionalHttpHeader, "The additional HTTP headers can not be null.");
 
+		Object dynamicRequestBody = createDynamicRequestBody(chatRequest);
 		// @formatter:off
 		return this.restClient.post()
 			.uri(this.completionsPath)
@@ -194,7 +198,7 @@ public ResponseEntity<ChatCompletion> chatCompletionEntity(ChatCompletionRequest
 				headers.addAll(additionalHttpHeader);
 				addDefaultHeadersIfMissing(headers);
 			})
-			.body(chatRequest)
+			.body(dynamicRequestBody)
 			.retrieve()
 			.toEntity(ChatCompletion.class);
 		// @formatter:on
@@ -210,6 +214,29 @@ public Flux<ChatCompletionChunk> chatCompletionStream(ChatCompletionRequest chat
 		return chatCompletionStream(chatRequest, new LinkedMultiValueMap<>());
 	}
 
+	private Object createDynamicRequestBody(ChatCompletionRequest baseRequest) {
+		ObjectMapper mapper = new ObjectMapper();
+		ObjectNode requestNode = mapper.valueToTree(baseRequest);
+		if (null == baseRequest.extraBody) {
+			return requestNode;
+		}
+
+		// 添加额外字段
+		baseRequest.extraBody().forEach((key, value) -> {
+			if (value instanceof Map) {
+				requestNode.set(key, mapper.valueToTree(value));
+			}
+			else if (value instanceof List) {
+				requestNode.set(key, mapper.valueToTree(value));
+			}
+			else {
+				requestNode.putPOJO(key, value);
+			}
+		});
+
+		return requestNode;
+	}
+
 	/**
 	 * Creates a streaming chat response for the given chat conversation.
 	 * @param chatRequest The chat completion request. Must have the stream property set
@@ -226,6 +253,15 @@ public Flux<ChatCompletionChunk> chatCompletionStream(ChatCompletionRequest chat
 
 		AtomicBoolean isInsideTool = new AtomicBoolean(false);
 
+		ObjectMapper objectMapper = new ObjectMapper();
+		try {
+			var s = objectMapper.writeValueAsString(chatRequest);
+			System.out.println("aaaaaaaa:" + s);
+		}
+		catch (JsonProcessingException e) {
+			throw new RuntimeException(e);
+		}
+		Object dynamicBody = createDynamicRequestBody(chatRequest);
 		// @formatter:off
 		return this.webClient.post()
 			.uri(this.completionsPath)
@@ -233,7 +269,7 @@ public Flux<ChatCompletionChunk> chatCompletionStream(ChatCompletionRequest chat
 				headers.addAll(additionalHttpHeader);
 				addDefaultHeadersIfMissing(headers);
 			}) // @formatter:on
-			.body(Mono.just(chatRequest), ChatCompletionRequest.class)
+			.bodyValue(dynamicBody)
 			.retrieve()
 			.bodyToFlux(String.class)
 			// cancels the flux stream after the "[DONE]" is received.
@@ -1116,7 +1152,8 @@ public record ChatCompletionRequest(// @formatter:off
 			@JsonProperty("user") String user,
 			@JsonProperty("reasoning_effort") String reasoningEffort,
 			@JsonProperty("web_search_options") WebSearchOptions webSearchOptions,
-			@JsonProperty("verbosity") String verbosity)  {
+			@JsonProperty("verbosity") String verbosity,
+			@JsonProperty("extra_body") Map<String, Object> extraBody) {
 
 		/**
 		 * Shortcut constructor for a chat completion request with the given messages, model and temperature.
@@ -1128,7 +1165,7 @@ public record ChatCompletionRequest(// @formatter:off
 		public ChatCompletionRequest(List<ChatCompletionMessage> messages, String model, Double temperature) {
 			this(messages, model, null, null, null, null, null, null, null, null, null, null, null, null, null,
 					null, null, null, false, null, temperature, null,
-					null, null, null, null, null, null, null);
+					null, null, null, null, null, null, null, null);
 		}
 
 		/**
@@ -1142,7 +1179,7 @@ public ChatCompletionRequest(List<ChatCompletionMessage> messages, String model,
 			this(messages, model, null, null, null, null, null, null,
 					null, null, null, List.of(OutputModality.AUDIO, OutputModality.TEXT), audio, null, null,
 					null, null, null, stream, null, null, null,
-					null, null, null, null, null, null, null);
+					null, null, null, null, null, null, null, null);
 		}
 
 		/**
@@ -1157,7 +1194,7 @@ public ChatCompletionRequest(List<ChatCompletionMessage> messages, String model,
 		public ChatCompletionRequest(List<ChatCompletionMessage> messages, String model, Double temperature, boolean stream) {
 			this(messages, model, null, null, null, null, null, null, null, null, null,
 					null, null, null, null, null, null, null, stream, null, temperature, null,
-					null, null, null, null, null, null, null);
+					null, null, null, null, null, null, null, null);
 		}
 
 		/**
@@ -1173,7 +1210,7 @@ public ChatCompletionRequest(List<ChatCompletionMessage> messages, String model,
 				List<FunctionTool> tools, Object toolChoice) {
 			this(messages, model, null, null, null, null, null, null, null, null, null,
 					null, null, null, null, null, null, null, false, null, 0.8, null,
-					tools, toolChoice, null, null, null, null, null);
+					tools, toolChoice, null, null, null, null, null, null);
 		}
 
 		/**
@@ -1184,9 +1221,9 @@ public ChatCompletionRequest(List<ChatCompletionMessage> messages, String model,
 		 * as they become available, with the stream terminated by a data: [DONE] message.
 		 */
 		public ChatCompletionRequest(List<ChatCompletionMessage> messages, Boolean stream) {
-			this(messages, null, null, null, null, null, null, null, null, null, null,
-					null, null, null, null, null, null, null, stream, null, null, null,
-					null, null, null, null, null, null, null);
+			this(messages, null, null, null, null, null, null, null, null, null, null, null, null, null,
+				null, null, null, null, stream, null, null, null, null, null, null, null, null, null,
+				null, null);
 		}
 
 		/**
@@ -1197,9 +1234,9 @@ public ChatCompletionRequest(List<ChatCompletionMessage> messages, Boolean strea
 		 */
 		public ChatCompletionRequest streamOptions(StreamOptions streamOptions) {
 			return new ChatCompletionRequest(this.messages, this.model, this.store, this.metadata, this.frequencyPenalty, this.logitBias, this.logprobs,
-			this.topLogprobs, this.maxTokens, this.maxCompletionTokens, this.n, this.outputModalities, this.audioParameters, this.presencePenalty,
-			this.responseFormat, this.seed, this.serviceTier, this.stop, this.stream, streamOptions, this.temperature, this.topP,
-			this.tools, this.toolChoice, this.parallelToolCalls, this.user, this.reasoningEffort, this.webSearchOptions, this.verbosity);
+					this.topLogprobs, this.maxTokens, this.maxCompletionTokens, this.n, this.outputModalities, this.audioParameters, this.presencePenalty,
+					this.responseFormat, this.seed, this.serviceTier, this.stop, this.stream, streamOptions, this.temperature, this.topP,
+					this.tools, this.toolChoice, this.parallelToolCalls, this.user, this.reasoningEffort, this.webSearchOptions, this.verbosity, this.extraBody);
 		}
 
 		/**
@@ -1411,7 +1448,8 @@ public record ChatCompletionMessage(// @formatter:off
 			@JsonProperty("tool_calls") @JsonFormat(with = JsonFormat.Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY) List<ToolCall> toolCalls,
 			@JsonProperty("refusal") String refusal,
 			@JsonProperty("audio") AudioOutput audioOutput,
-			@JsonProperty("annotations") List<Annotation> annotations
+			@JsonProperty("annotations") List<Annotation> annotations,
+			@JsonProperty("reasoning_content") String reasoningContent
 	) { // @formatter:on
 
 		/**
@@ -1421,7 +1459,7 @@ public record ChatCompletionMessage(// @formatter:off
 		 * @param role The role of the author of this message.
 		 */
 		public ChatCompletionMessage(Object content, Role role) {
-			this(content, role, null, null, null, null, null, null);
+			this(content, role, null, null, null, null, null, null, null);
 		}
 
 		/**
diff --git a/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiStreamFunctionCallingHelper.java b/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiStreamFunctionCallingHelper.java
index 55d74fa7b52..3558760a54f 100644
--- a/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiStreamFunctionCallingHelper.java
+++ b/models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiStreamFunctionCallingHelper.java
@@ -36,6 +36,7 @@
 /**
  * Helper class to support Streaming function calling.
  *
+ * <p>
  * It can merge the streamed ChatCompletionChunk in case of function calling message.
  *
  * @author Christian Tzolov
@@ -100,6 +101,8 @@ private ChunkChoice merge(ChunkChoice previous, ChunkChoice current) {
 	private ChatCompletionMessage merge(ChatCompletionMessage previous, ChatCompletionMessage current) {
 		String content = (current.content() != null ? current.content()
 				: "" + ((previous.content() != null) ? previous.content() : ""));
+		String reasoningContent = (current.reasoningContent() != null ? current.reasoningContent()
+				: "" + ((previous.reasoningContent() != null) ? previous.reasoningContent() : ""));
 		Role role = (current.role() != null ? current.role() : previous.role());
 		role = (role != null ? role : Role.ASSISTANT); // default to ASSISTANT (if null
 		String name = (current.name() != null ? current.name() : previous.name());
@@ -138,7 +141,8 @@ private ChatCompletionMessage merge(ChatCompletionMessage previous, ChatCompleti
 				toolCalls.add(lastPreviousTooCall);
 			}
 		}
-		return new ChatCompletionMessage(content, role, name, toolCallId, toolCalls, refusal, audioOutput, annotations);
+		return new ChatCompletionMessage(content, role, name, toolCallId, toolCalls, refusal, audioOutput, annotations,
+				reasoningContent);
 	}
 
 	private ToolCall merge(ToolCall previous, ToolCall current) {
diff --git a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiApiBuilderTests.java b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiApiBuilderTests.java
index e2858c9e46d..01b7635418c 100644
--- a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiApiBuilderTests.java
+++ b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiApiBuilderTests.java
@@ -412,6 +412,7 @@ void dynamicApiKeyWebClient() throws InterruptedException {
 									"role": "assistant",
 									"content": "Hello world"
 									},
+									"reasoning_content": "test",
 									"finish_reason": "stop"
 								}
 							],
diff --git a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiApiIT.java b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiApiIT.java
index d050a621034..55c223d818a 100644
--- a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiApiIT.java
+++ b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiApiIT.java
@@ -77,7 +77,7 @@ void validateReasoningTokens() {
 				"If a train travels 100 miles in 2 hours, what is its average speed?", ChatCompletionMessage.Role.USER);
 		ChatCompletionRequest request = new ChatCompletionRequest(List.of(userMessage), "o1", null, null, null, null,
 				null, null, null, null, null, null, null, null, null, null, null, null, false, null, null, null, null,
-				null, null, null, "low", null, null);
+				null, null, null, "low", null, null, null);
 		ResponseEntity<ChatCompletion> response = this.openAiApi.chatCompletionEntity(request);
 
 		assertThat(response).isNotNull();
@@ -180,7 +180,7 @@ void chatCompletionEntityWithNewModelsAndLowVerbosity(OpenAiApi.ChatModel modelN
 
 		ChatCompletionRequest request = new ChatCompletionRequest(List.of(chatCompletionMessage), // messages
 				modelName.getValue(), null, null, null, null, null, null, null, null, null, null, null, null, null,
-				null, null, null, false, null, 1.0, null, null, null, null, null, null, null, "low");
+				null, null, null, false, null, 1.0, null, null, null, null, null, null, null, "low", null);
 
 		ResponseEntity<ChatCompletion> response = this.openAiApi.chatCompletionEntity(request);
 
@@ -227,7 +227,7 @@ void chatCompletionEntityWithServiceTier(OpenAiApi.ServiceTier serviceTier) {
 		ChatCompletionRequest request = new ChatCompletionRequest(List.of(chatCompletionMessage), // messages
 				OpenAiApi.ChatModel.GPT_4_O.value, null, null, null, null, null, null, null, null, null, null, null,
 				null, null, null, serviceTier.getValue(), null, false, null, 1.0, null, null, null, null, null, null,
-				null, null);
+				null, null, null);
 
 		ResponseEntity<ChatCompletion> response = this.openAiApi.chatCompletionEntity(request);
 
diff --git a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiStreamFunctionCallingHelperTest.java b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiStreamFunctionCallingHelperTest.java
index d67245dc49e..6e9967908e5 100644
--- a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiStreamFunctionCallingHelperTest.java
+++ b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/OpenAiStreamFunctionCallingHelperTest.java
@@ -88,8 +88,8 @@ public void isStreamingToolFunctionCall_whenChatCompletionChunkFirstChoiceDeltaT
 		// Test for null.
 		assertion.accept(new OpenAiApi.ChatCompletionMessage(null, null));
 		// Test for empty.
-		assertion.accept(
-				new OpenAiApi.ChatCompletionMessage(null, null, null, null, Collections.emptyList(), null, null, null));
+		assertion.accept(new OpenAiApi.ChatCompletionMessage(null, null, null, null, Collections.emptyList(), null,
+				null, null, null));
 	}
 
 	@Test
@@ -102,7 +102,7 @@ public void isStreamingToolFunctionCall_whenChatCompletionChunkFirstChoiceDeltaT
 		};
 		assertion.accept(new OpenAiApi.ChatCompletionMessage(null, null, null, null,
 				List.of(Mockito.mock(org.springframework.ai.openai.api.OpenAiApi.ChatCompletionMessage.ToolCall.class)),
-				null, null, null));
+				null, null, null, null));
 	}
 
 	@Test
@@ -191,7 +191,8 @@ public void isStreamingToolFunctionCallReturnsFalseForNullOrEmptyChunks() {
 	@Test
 	public void isStreamingToolFunctionCall_returnsTrueForValidToolCalls() {
 		var toolCall = Mockito.mock(OpenAiApi.ChatCompletionMessage.ToolCall.class);
-		var delta = new OpenAiApi.ChatCompletionMessage(null, null, null, null, List.of(toolCall), null, null, null);
+		var delta = new OpenAiApi.ChatCompletionMessage(null, null, null, null, List.of(toolCall), null, null, null,
+				null);
 		var choice = new OpenAiApi.ChatCompletionChunk.ChunkChoice(null, null, delta, null);
 		var chunk = new OpenAiApi.ChatCompletionChunk(null, List.of(choice), null, null, null, null, null, null);
 
@@ -255,7 +256,7 @@ public void merge_partialFieldsFromEachChunk() {
 	public void isStreamingToolFunctionCall_withMultipleChoicesAndOnlyFirstHasToolCalls() {
 		var toolCall = Mockito.mock(OpenAiApi.ChatCompletionMessage.ToolCall.class);
 		var deltaWithToolCalls = new OpenAiApi.ChatCompletionMessage(null, null, null, null, List.of(toolCall), null,
-				null, null);
+				null, null, null);
 		var deltaWithoutToolCalls = new OpenAiApi.ChatCompletionMessage(null, null);
 
 		var choice1 = new OpenAiApi.ChatCompletionChunk.ChunkChoice(null, null, deltaWithToolCalls, null);
@@ -327,7 +328,7 @@ public void edgeCases_emptyStringFields() {
 
 	@Test
 	public void isStreamingToolFunctionCall_withNullToolCallsList() {
-		var delta = new OpenAiApi.ChatCompletionMessage(null, null, null, null, null, null, null, null);
+		var delta = new OpenAiApi.ChatCompletionMessage(null, null, null, null, null, null, null, null, null);
 		var choice = new OpenAiApi.ChatCompletionChunk.ChunkChoice(null, null, delta, null);
 		var chunk = new OpenAiApi.ChatCompletionChunk(null, List.of(choice), null, null, null, null, null, null);
 
diff --git a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/tool/OpenAiApiToolFunctionCallIT.java b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/tool/OpenAiApiToolFunctionCallIT.java
index e655de46421..3ce6e3f24e6 100644
--- a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/tool/OpenAiApiToolFunctionCallIT.java
+++ b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/tool/OpenAiApiToolFunctionCallIT.java
@@ -130,7 +130,7 @@ public void toolFunctionCall() {
 
 				// extend conversation with function response.
 				messages.add(new ChatCompletionMessage("" + weatherResponse.temp() + weatherRequest.unit(), Role.TOOL,
-						functionName, toolCall.id(), null, null, null, null));
+						functionName, toolCall.id(), null, null, null, null, null));
 			}
 		}
 
diff --git a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/chat/OpenAiStreamingFinishReasonTests.java b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/chat/OpenAiStreamingFinishReasonTests.java
index 3dc59444e82..1664782314b 100644
--- a/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/chat/OpenAiStreamingFinishReasonTests.java
+++ b/models/spring-ai-openai/src/test/java/org/springframework/ai/openai/chat/OpenAiStreamingFinishReasonTests.java
@@ -124,7 +124,8 @@ void testJsonDeserializationWithEmptyStringFinishReason() throws JsonProcessingE
 						"index": 0,
 						"delta": {
 							"role": "assistant",
-							"content": ""
+							"content": "",
+							"reasoning_content": ""
 						},
 						"finish_reason": ""
 					}]
@@ -161,7 +162,8 @@ void testJsonDeserializationWithNullFinishReason() throws JsonProcessingExceptio
 						"index": 0,
 						"delta": {
 							"role": "assistant",
-							"content": "Hello"
+							"content": "Hello",
+							"reasoning_content": "test"
 						},
 						"finish_reason": null
 					}]
@@ -176,6 +178,7 @@ void testJsonDeserializationWithNullFinishReason() throws JsonProcessingExceptio
 		var choice = chunk.choices().get(0);
 		assertThat(choice.finishReason()).isNull();
 		assertThat(choice.delta().content()).isEqualTo("Hello");
+		assertThat(choice.delta().reasoningContent()).isEqualTo("test");
 	}
 
 	@Test