diff --git a/arlbench/autorl/autorl_env.py b/arlbench/autorl/autorl_env.py
index a15523f07..4cb103a20 100644
--- a/arlbench/autorl/autorl_env.py
+++ b/arlbench/autorl/autorl_env.py
@@ -37,6 +37,8 @@
     "env_name": "CartPole-v1",
     "env_kwargs": {},
     "eval_env_kwargs": {},
+    "env_params": {},
+    "env_eval_params": {},
     "n_envs": 10,
     "algorithm": "dqn",
     "cnn_policy": False,
@@ -107,6 +109,7 @@ def __init__(self, config: dict | None = None) -> None:
             env_kwargs=self._config["env_kwargs"],
             cnn_policy=self._config["cnn_policy"],
             seed=self._seed,
+            env_params=self._config.get("env_params", None)
         )
 
         self._eval_env = make_env(
@@ -116,6 +119,7 @@ def __init__(self, config: dict | None = None) -> None:
             env_kwargs=self._config["eval_env_kwargs"],
             cnn_policy=self._config["cnn_policy"],
             seed=self._seed + 1,
+            env_params=self._config.get("env_eval_params", None)
         )
 
         # Checkpointing
diff --git a/arlbench/core/environments/gymnax_env.py b/arlbench/core/environments/gymnax_env.py
index 120974de1..c64277815 100644
--- a/arlbench/core/environments/gymnax_env.py
+++ b/arlbench/core/environments/gymnax_env.py
@@ -6,6 +6,7 @@
 
 import gymnax
 import jax
+from dataclasses import replace
 
 from .autorl_env import Environment
 
@@ -17,7 +18,7 @@ class GymnaxEnv(Environment):
     """A gymnax-based RL environment."""
 
     def __init__(
-        self, env_name: str, n_envs: int, env_kwargs: dict[str, Any] | None = None
+        self, env_name: str, n_envs: int, env_kwargs: dict[str, Any] | None = None, env_params: dict[str, Any] | None = None
     ):
         """Creates a gymnax environment for JAX-based RL training.
 
@@ -29,7 +30,8 @@ def __init__(
         """
         if env_kwargs is None:
             env_kwargs = {}
-        env, env_params = gymnax.make(env_name, **env_kwargs)
+        env, og_env_params = gymnax.make(env_name, **env_kwargs)
+        env_params = replace(og_env_params, **(env_params or {}))
         super().__init__(env_name, env, n_envs)
 
         self.env_params = env_params
diff --git a/arlbench/core/environments/make_env.py b/arlbench/core/environments/make_env.py
index 1ffb4c7e6..00a645a1e 100644
--- a/arlbench/core/environments/make_env.py
+++ b/arlbench/core/environments/make_env.py
@@ -19,6 +19,7 @@ def make_env(
     n_envs: int = 1,
     seed: int = 0,
     env_kwargs: dict[str, Any] | None = None,
+    env_params: dict[str, Any] | None = None,
 ) -> Environment | Wrapper:
     """ARLBench equivalent to make_env in gymnasium/gymnax etc.
     Creates a JAX-compatible RL environment.
@@ -50,7 +51,7 @@ def make_env(
     elif env_framework == "gymnax":
         from .gymnax_env import GymnaxEnv
 
-        env = GymnaxEnv(env_name, n_envs, env_kwargs=env_kwargs)
+        env = GymnaxEnv(env_name, n_envs, env_kwargs=env_kwargs, env_params=env_params)
     elif env_framework == "envpool":
         from .envpool_env import EnvpoolEnv
 
diff --git a/examples/configs/base.yaml b/examples/configs/base.yaml
index 3445ed89e..3770d1e23 100644
--- a/examples/configs/base.yaml
+++ b/examples/configs/base.yaml
@@ -20,6 +20,7 @@ autorl:
   env_framework: ${environment.framework}
   env_name: ${environment.name}
   env_kwargs: ${environment.kwargs}
+  env_params: ${environment.env_params}
   eval_env_kwargs: ${environment.eval_kwargs}
   n_envs: ${environment.n_envs}
   algorithm: ${algorithm}
diff --git a/examples/configs/environment/cc_cartpole.yaml b/examples/configs/environment/cc_cartpole.yaml
index d789c0dfb..d478d18bd 100644
--- a/examples/configs/environment/cc_cartpole.yaml
+++ b/examples/configs/environment/cc_cartpole.yaml
@@ -7,3 +7,7 @@ cnn_policy: False
 deterministic_eval: True
 jax_enable_x64: False
 n_envs: 8
+
+env_params:
+  masspole: 0.9
+  length: 0.7