diff --git a/apps/api/src/utils/git_history.py b/apps/api/src/utils/git_history.py
index 7bc9e03..8dae1dd 100644
--- a/apps/api/src/utils/git_history.py
+++ b/apps/api/src/utils/git_history.py
@@ -2,6 +2,7 @@
 
 import subprocess
 from dataclasses import dataclass
+from datetime import datetime, timezone
 from typing import Any
 
 
@@ -182,10 +183,10 @@ def get_commit_detail(repo_path: str, commit_hash: str) -> dict[str, Any]:
         "parents": parents,
         "author_name": author,
         "author_email": email,
-        "author_date": str(timestamp),
+        "author_date": datetime.fromtimestamp(timestamp, tz=timezone.utc).isoformat(),
         "committer_name": author,  # TODO: extract committer separately
         "committer_email": email,  # TODO: extract committer separately
-        "committer_date": str(timestamp),
+        "committer_date": datetime.fromtimestamp(timestamp, tz=timezone.utc).isoformat(),
         "message": message,
         "body": body,
         "branches": branch_map.get(commit_hash, []),
@@ -361,7 +362,7 @@ def _commit_to_dict(commit: Commit, graph_symbol: str = "", graph_depth: int = 0
         "parents": commit.parents,
         "author_name": commit.author,
         "author_email": commit.email,
-        "author_date": str(commit.timestamp),
+        "author_date": datetime.fromtimestamp(commit.timestamp, tz=timezone.utc).isoformat(),
         "message": commit.message,
         "refs": refs,
         "graph_symbol": graph_symbol,