diff --git a/tests/unit_tests/test_special_characters.py b/tests/unit_tests/test_special_characters.py
new file mode 100644
index 00000000..97ba7790
--- /dev/null
+++ b/tests/unit_tests/test_special_characters.py
@@ -0,0 +1,254 @@
+import json
+import sys
+import unittest
+from pathlib import Path
+from unittest.mock import MagicMock
+
+from pymysql.converters import escape_string
+
+# Ensure local src/ is on sys.path
+project_root = Path(__file__).parent.parent.parent
+src_root = project_root / "src"
+sys.path.insert(0, str(src_root))
+
+from pyseekdb.client.client_base import BaseClient  # noqa: E402
+from pyseekdb.client.collection import Collection  # noqa: E402
+
+
+class MockClient(BaseClient):
+    """Mock client for testing SQL generation without actual DB connection."""
+
+    def __init__(self):
+        """Initialize MockClient with a mock executor."""
+        self._executor = MagicMock()
+
+    def _execute(self, sql):
+        """Execute SQL statement using mock executor.
+
+        Args:
+            sql: SQL statement to execute.
+
+        Returns:
+            Result from mock executor.
+        """
+        return self._executor(sql)
+
+    @property
+    def mode(self):
+        """Return the client mode.
+
+        Returns:
+            str: Mode identifier ('mock').
+        """
+        return "mock"
+
+    def is_connected(self) -> bool:
+        """Check if client is connected.
+
+        Returns:
+            bool: Always True for mock client.
+        """
+        return True
+
+    def get_raw_connection(self):
+        """Get raw database connection.
+
+        Returns:
+            MagicMock: Mock connection object.
+        """
+        return MagicMock()
+
+    def _ensure_connection(self):
+        """Ensure connection is established.
+
+        Returns:
+            MagicMock: Mock connection.
+        """
+        return MagicMock()
+
+    def _cleanup(self):
+        """Clean up resources."""
+        pass
+
+    # Implement abstract methods with dummies
+    def create_collection(self, name, configuration=None, embedding_function=None, **kwargs):
+        """Create a collection (not implemented for mock)."""
+        pass
+
+    def get_collection(self, name, embedding_function=None):
+        """Get a collection (not implemented for mock)."""
+        pass
+
+    def delete_collection(self, name):
+        """Delete a collection (not implemented for mock)."""
+        pass
+
+    def list_collections(self):
+        """List collections (not implemented for mock)."""
+        pass
+
+    def has_collection(self, name):
+        """Check if collection exists (not implemented for mock)."""
+        pass
+
+
+class TestSpecialCharacters(unittest.TestCase):
+    """Tests for handling special characters in all fields (ids, documents, metadatas)."""
+
+    def setUp(self):
+        self.client = MockClient()
+        # Mock connection check
+        self.client._ensure_connection = MagicMock()
+        self.client._use_context_manager_for_cursor = MagicMock(return_value=False)
+
+        # Create a dummy collection
+        self.collection_name = "test_collection"
+        self.collection = Collection(client=self.client, name=self.collection_name, collection_id="test_id_123")
+
+        # Define special test cases
+        self.special_chars = [
+            # SQL Injection attempts
+            "' OR '1'='1",
+            "'; DROP TABLE users; --",
+            "admin' --",
+            '"',
+            "`",
+            # Special syntax characters
+            "\\",
+            "\\\\",
+            "\n",
+            "\r",
+            "\t",
+            "\0",
+            # Unicode and Languages
+            "中文测试",
+            "ñandú",
+            "München",
+            "עִבְרִית",  # Hebrew
+            "العربية",  # Arabic
+            # Emojis
+            "😀",
+            "👨‍👩‍👧‍👦",
+            "🔥",
+            # Whitespace
+            "   ",
+            " ",
+        ]
+
+    def test_ids_special_characters(self):
+        """Test that IDs with special characters are correctly escaped and cast to BINARY."""
+        for special_str in self.special_chars:
+            # We explicitly test the internal SQL conversion method for IDs
+            sql = self.client._convert_id_to_sql(special_str)
+
+            # Basic checks
+            self.assertIn("CAST(", sql)
+            self.assertIn("AS BINARY)", sql)
+
+            # If it contains a single quote, it should be escaped
+            if "'" in special_str:
+                # The raw string in SQL should have escaped quotes
+                # e.g. ' becomes \' or '' depending on the escaper
+                # pymysql escape_string usually uses backslash
+                pass
+
+            # Now try adding it to collection via internal method
+            self.client._executor.reset_mock()
+            self.client._collection_add(
+                collection_id=self.collection.id,
+                collection_name=self.collection.name,
+                ids=[special_str],
+                embeddings=[[0.1, 0.2]],  # Dummy embedding
+            )
+
+            # Check the executed SQL
+            call_args = self.client._executor.call_args
+            self.assertIsNotNone(call_args)
+            executed_sql = call_args[0][0]
+            self.assertIn("INSERT INTO", executed_sql)
+            self.assertIn("_id", executed_sql)
+            self.assertIn(self.collection.id, executed_sql)
+
+            # Verify the ID is in the SQL and is correctly escaped
+            expected_id_segment = escape_string(special_str)
+            self.assertIn(expected_id_segment, executed_sql)
+
+    def test_documents_special_characters(self):
+        """Test that documents with special characters are correctly escaped."""
+        for special_str in self.special_chars:
+            self.client._executor.reset_mock()
+
+            self.client._collection_add(
+                collection_id=self.collection.id,
+                collection_name=self.collection.name,
+                ids=["id_1"],
+                documents=[special_str],
+                embeddings=[[0.1, 0.2]],
+            )
+
+            call_args = self.client._executor.call_args
+            executed_sql = call_args[0][0]
+            self.assertIn("INSERT INTO", executed_sql)
+            self.assertIn("_id", executed_sql)
+            self.assertIn(self.collection.id, executed_sql)
+
+            # Verify content is in SQL and correctly escaped
+            expected_doc_segment = escape_string(special_str)
+            self.assertIn(expected_doc_segment, executed_sql)
+            # We rely on pymysql.converters.escape_string which is trusted,
+            # ensuring we pass it through.
+            pass
+
+    def test_metadata_special_characters(self):
+        """Test that metadata keys and values with special characters are correctly handled."""
+        for special_str in self.special_chars:
+            self.client._executor.reset_mock()
+
+            # Test as value
+            metadata = {"key": special_str}
+
+            # Test as key (keys in JSON usually string, but worth testing escaping)
+            # Note: JSON keys must be strings.
+            metadata_key_test = {special_str: "value"}
+            self.assertIn(special_str, metadata_key_test)
+
+            self.client._collection_add(
+                collection_id=self.collection.id,
+                collection_name=self.collection.name,
+                ids=["id_val"],
+                embeddings=[[0.1, 0.2]],
+                metadatas=[metadata],
+            )
+
+            call_args = self.client._executor.call_args
+            executed_sql = call_args[0][0]
+            self.assertIn("INSERT INTO", executed_sql)
+            self.assertIn("_id", executed_sql)
+            self.assertIn(self.collection.id, executed_sql)
+
+            # Verify JSON serialization and SQL escaping
+            # json.dumps handles special chars inside JSON string
+            # escape_string handles the SQL level escaping
+            expected_meta_segment = escape_string(json.dumps(metadata, ensure_ascii=False))
+            self.assertIn(expected_meta_segment, executed_sql)
+
+    def test_collection_name_special_characters(self):
+        """
+        Verify validation of collection names with special characters.
+        BaseClient._validate_collection_name enforces strict rules.
+        """
+        from pyseekdb.client.client_base import _validate_collection_name
+
+        # Valid name
+        _validate_collection_name("valid_name_123")
+
+        # Invalid names (should raise ValueError)
+        invalid_names = ["name with spaces", "name-with-dash", "name.with.dot", "name@symbol", "中文", "test\nname"]
+
+        for name in invalid_names:
+            with self.assertRaises(ValueError):
+                _validate_collection_name(name)
+
+
+if __name__ == "__main__":
+    unittest.main()