Abstract: The effect of H₂ on the corrosion dynamics of low carbon steel in coke oven gas was investigated. It is showed that the electropolar process controlling step changes remarkably at 0.15g/m³ H₂,corrosion controlling step is cathodic reactions at<0.15g/m³ H₂ and anodic reactions at>0.15g/m³H₂.There is evidence that the dense protective film forms on the surface of low carbon steel in high H₂ coke oven gas. The phenomena are theoretically explained.