diff --git a/tests/sdk/llm/test_gpt5_mini_temperature_issue.py b/tests/sdk/llm/test_gpt5_mini_temperature_issue.py
new file mode 100644
index 0000000000..d601fcfa97
--- /dev/null
+++ b/tests/sdk/llm/test_gpt5_mini_temperature_issue.py
@@ -0,0 +1,130 @@
+"""Test for GPT-5-mini temperature issue with litellm_proxy.
+
+This test reproduces the issue where GPT-5-mini requires temperature to be set to 1,
+but the LLM class defaults to temperature=0.0, causing an error.
+
+These tests use real LLM API calls and require LLM_API_KEY and LLM_BASE_URL
+environment variables to be set.
+"""
+
+import os
+
+import pytest
+from pydantic import SecretStr
+
+from openhands.sdk.llm import LLM
+
+
+def get_llm_config():
+    """Get LLM configuration from environment variables."""
+    api_key = os.getenv("LLM_API_KEY")
+    base_url = os.getenv("LLM_BASE_URL")
+
+    if not api_key or not base_url:
+        pytest.skip(
+            "LLM_API_KEY and LLM_BASE_URL environment variables must be set "
+            "to run real LLM tests"
+        )
+
+    return api_key, base_url
+
+
+def test_gpt5_mini_temperature_issue_without_temperature():
+    """Test that GPT-5-mini fails when temperature is not explicitly set to 1.
+
+    This test reproduces the issue where GPT-5-mini requires temperature=1
+    but the LLM class defaults to temperature=0.0, causing an error.
+    """
+    api_key, base_url = get_llm_config()
+
+    # Create LLM with litellm_proxy/openai/gpt-5-mini without specifying temperature
+    # This should use the default temperature=0.0
+    llm = LLM(
+        model="litellm_proxy/openai/gpt-5-mini",
+        api_key=SecretStr(api_key),
+        base_url=base_url,
+        num_retries=1,  # Reduce retries for faster test
+        retry_min_wait=1,
+        retry_max_wait=2,
+    )
+
+    # Verify that the LLM has the default temperature of 0.0
+    assert llm.temperature == 0.0
+
+    # Try to use the completion API - this should fail with GPT-5-mini
+    messages = [{"role": "user", "content": "Hello, GPT-5-mini!"}]
+
+    # The exact error message may vary depending on the LLM proxy implementation
+    # but it should fail when temperature is not 1.0 for GPT-5-mini
+    with pytest.raises(Exception) as exc_info:
+        llm.completion(messages=messages)
+
+    # Check that the error is related to temperature requirements
+    error_message = str(exc_info.value).lower()
+    assert "temperature" in error_message or "parameter" in error_message
+
+
+def test_gpt5_mini_works_with_temperature_1():
+    """Test that GPT-5-mini works when temperature is explicitly set to 1.
+
+    This test shows that the issue can be resolved by explicitly setting temperature=1.
+    """
+    api_key, base_url = get_llm_config()
+
+    # Create LLM with litellm_proxy/openai/gpt-5-mini with temperature=1.0
+    llm = LLM(
+        model="litellm_proxy/openai/gpt-5-mini",
+        api_key=SecretStr(api_key),
+        base_url=base_url,
+        temperature=1.0,  # Explicitly set temperature to 1.0
+        num_retries=1,
+        retry_min_wait=1,
+        retry_max_wait=2,
+    )
+
+    # Verify that the LLM has temperature set to 1.0
+    assert llm.temperature == 1.0
+
+    # Try to use the completion API - this should work
+    messages = [{"role": "user", "content": "Hello, GPT-5-mini!"}]
+
+    response = llm.completion(messages=messages)
+
+    # Verify the response
+    assert response is not None
+    assert len(response.choices) > 0
+    assert response.choices[0].message.content is not None  # type: ignore
+    assert len(response.choices[0].message.content.strip()) > 0  # type: ignore
+
+
+def test_gpt5_mini_temperature_override_in_completion_call():
+    """Test that temperature can be overridden in the completion call.
+
+    This test shows that even if the LLM has a default temperature,
+    it can be overridden in the completion call.
+    """
+    api_key, base_url = get_llm_config()
+
+    # Create LLM with litellm_proxy/openai/gpt-5-mini with default temperature=0.0
+    llm = LLM(
+        model="litellm_proxy/openai/gpt-5-mini",
+        api_key=SecretStr(api_key),
+        base_url=base_url,
+        num_retries=1,
+        retry_min_wait=1,
+        retry_max_wait=2,
+    )
+
+    # Verify that the LLM has the default temperature of 0.0
+    assert llm.temperature == 0.0
+
+    # Try to use the completion API with temperature=1.0 override - this should work
+    messages = [{"role": "user", "content": "Hello, GPT-5-mini!"}]
+
+    response = llm.completion(messages=messages, temperature=1.0)
+
+    # Verify the response
+    assert response is not None
+    assert len(response.choices) > 0
+    assert response.choices[0].message.content is not None  # type: ignore
+    assert len(response.choices[0].message.content.strip()) > 0  # type: ignore