Abstract: A chromium-free water based coating for treating a galvannealed or galvanized steel surface. The coating is based upon a hybrid condensation product of a water soluble sol-gel solution prepared from a solution containing one or more organo-functional silanes. The silane solution is hydrolised at pH 4-6.5 for 16 hours at room temperature with continuous stirring at a speed of 300-800 rpm. The coating composition when applied on a galvanized or galvannealed steel substrate provides more than 200 hours of white rust resistance at a coating thickness of less than 5 micron and can dry within 10-30 seconds at 80-90° C. peak metal temperature.