diff --git a/src/sssom/sexpr.py b/src/sssom/sexpr.py
new file mode 100644
index 00000000..b988fcf6
--- /dev/null
+++ b/src/sssom/sexpr.py
@@ -0,0 +1,74 @@
+"""Generate canonical s-expressions and mapping hashes."""
+
+import hashlib
+import re
+import unittest
+
+import zbase32
+
+from sssom import Mapping
+from sssom.constants import _get_sssom_schema_object
+
+__all__ = [
+    "get_mapping_hash",
+]
+
+def get_mapping_hash(x: Mapping) -> str:
+    """Hash the mapping by converting to canonical s-expression, sha256 hashing, then zbase32 encoding."""
+    s = hashlib.sha256()
+    s.update(to_sexpr(x).encode("utf-8"))
+    dig = s.digest()
+    return zbase32.encode(dig)
+
+
+SKIP_SLOTS = {"record_id", "mapping_cardinality"}
+
+
+def to_sexpr(x: Mapping) -> str:
+    # todo get canonical order
+    rv = "(7:mapping("
+    for slot in _get_sssom_schema_object().slots:
+        if slot in SKIP_SLOTS:
+            continue
+        value = getattr(x, slot, None)
+        if not value:
+            continue
+        elif isinstance(value, str):
+            rv += f"({len(slot)}:{slot}{len(value)}:{value})"
+        elif isinstance(value, float):
+            raise NotImplementedError
+        elif isinstance(value, list):
+            rv += f"({len(slot)}:{slot}("
+            for v in value:
+                rv += f"{len(v)}:{v}"
+            rv += "))"
+    return rv + "))"
+
+
+class TestSExpressions(unittest.TestCase):
+    def test_big_example(self) -> None:
+        """"""
+        s = """
+        (7:mapping(
+           (10:subject_id44:http://purl.obolibrary.org/obo/FBbt_00001234)
+           (12:predicate_id46:http://www.w3.org/2004/02/skos/core#exactMatch)
+           (9:object_id45:http://purl.obolibrary.org/obo/UBERON_0005678)
+           (21:mapping_justification51:https://w3id.org/semapv/vocab/ManualMappingCuration)
+           (10:creator_id(
+                          37:https://orcid.org/0000-0000-1234-5678
+                          37:https://orcid.org/0000-0000-5678-1234
+            ))
+        ))
+        """
+        x = Mapping(
+            subject_id="http://purl.obolibrary.org/obo/FBbt_00001234",
+            predicate_id="http://www.w3.org/2004/02/skos/core#exactMatch",
+            object_id="http://purl.obolibrary.org/obo/UBERON_0005678",
+            mapping_justification="https://w3id.org/semapv/vocab/ManualMappingCuration",
+            creator_id=[
+                "https://orcid.org/0000-0000-1234-5678",
+                "https://orcid.org/0000-0000-5678-1234",
+            ],
+        )
+        self.assertEqual(re.sub("\s", "", s), to_sexpr(x))
+        self.assertEqual("hq6bs14aptzepwgk6pw7j8ysnft6riqrw7har84rtk8r9xmbcwty", get_mapping_hash(x))