diff --git a/backend/tests/test_rag_service.py b/backend/tests/test_rag_service.py
new file mode 100644
index 00000000..e20f32ed
--- /dev/null
+++ b/backend/tests/test_rag_service.py
@@ -0,0 +1,110 @@
+import pytest
+from unittest.mock import MagicMock, patch
+import sys
+import os
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..'))
+
+import importlib.util
+
+spec = importlib.util.spec_from_file_location(
+    "rag_service",
+    "/home/itsmaestro/gssoc/HELPDESK.AI/backend/services/rag_service.py"
+)
+rag_module = importlib.util.module_from_spec(spec)
+sys.modules['backend.services.rag_service'] = rag_module
+spec.loader.exec_module(rag_module)
+
+
+class TestRagServiceInit:
+    def test_init_sets_defaults(self):
+        service = rag_module.RagService()
+        assert service.model is None
+        assert service._loaded is False
+        assert service._load_failed is False
+
+
+class TestRagServiceAvailability:
+    def test_is_available_when_not_loaded(self):
+        service = rag_module.RagService()
+        assert service.is_available() is False
+
+    def test_is_available_when_load_failed(self):
+        service = rag_module.RagService()
+        service._load_failed = True
+        assert service.is_available() is False
+
+
+class TestRagServiceLoad:
+    def test_load_without_sentence_transformers(self):
+        original_has_sentence = rag_module._HAS_SENTENCE
+        rag_module._HAS_SENTENCE = False
+        try:
+            with patch.dict(os.environ, {"ALLOW_DEGRADED_STARTUP": "1"}):
+                service = rag_module.RagService()
+                service.load()
+                assert service._load_failed is True
+        finally:
+            rag_module._HAS_SENTENCE = original_has_sentence
+
+    def test_load_idempotent(self):
+        service = rag_module.RagService()
+        service._loaded = True
+        service.load()
+        assert service._loaded is True
+
+
+class TestRagServiceSearchKnowledgeBase:
+    def test_search_returns_none_when_not_loaded(self):
+        service = rag_module.RagService()
+        result = service.search_knowledge_base("test query")
+        assert result is None
+
+    def test_search_returns_none_when_load_failed(self):
+        service = rag_module.RagService()
+        service._load_failed = True
+        result = service.search_knowledge_base("test query")
+        assert result is None
+
+    def test_search_returns_none_without_supabase(self):
+        service = rag_module.RagService()
+        service._loaded = True
+        service.supabase = None
+        result = service.search_knowledge_base("test query")
+        assert result is None
+
+    def test_search_with_mock_response(self):
+        service = rag_module.RagService()
+        service._loaded = True
+        mock_supabase = MagicMock()
+        mock_response = MagicMock()
+        mock_response.data = [
+            {
+                "id": 1,
+                "title": "Test Article",
+                "content": "Test content",
+                "similarity": 0.95
+            }
+        ]
+        mock_supabase.rpc.return_value.execute.return_value = mock_response
+        service.supabase = mock_supabase
+        service.model = MagicMock()
+        service.model.encode.return_value = MagicMock(tolist=lambda: [0.1] * 384)
+        result = service.search_knowledge_base("test query")
+        assert result is not None
+        assert result["title"] == "Test Article"
+        assert result["content"] == "Test content"
+        assert result["similarity"] == 0.95
+
+    def test_search_with_no_matches(self):
+        service = rag_module.RagService()
+        service._loaded = True
+        mock_supabase = MagicMock()
+        mock_response = MagicMock()
+        mock_response.data = []
+        mock_supabase.rpc.return_value.execute.return_value = mock_response
+        service.supabase = mock_supabase
+        service.model = MagicMock()
+        service.model.encode.return_value = MagicMock(tolist=lambda: [0.1] * 384)
+        result = service.search_knowledge_base("test query")
+        assert result is None