Carbon-carbon composites are widely used in aerospace industry due to their unique combination of high strength and low density. However, for high temperature applications in an oxidative atmosphere they must be protected by refractory coating. A simple method is proposed to apply a gas-phase coating on carbon-carbon composites surface from a low cost precursor. The coating fully infiltrates the C-C surface to the depth of 0.5-1mm (0.020-0.040"). The surface of each carbon fiber in the infiltrated layer is fully converted into silicon carbide. This method provides a continuous coating which is highly adherent to the carbon-carbon surface. The coated C-C samples were tested by acetylene torch in air at 1800°C/3272°F for 5min and showed 35 times smaller ablation rate than uncoated ones. Testing in air with high velocity plasma flow perpendicular to the tested surface at 3500°C/6330°F for 30sec demonstrated great advantage of the coated sample over the uncoated one.