The effect of 0.5-2.0% Cu addition on the corrosion resistance and polarization behavior of 304 (UNS S 30 400) austenitic stainless steel in deaerated 1 N H2SO4 at 20-80 degrees C has been investigated by potentiodynamic, scanning electron microscopic and energy dispersive X-ray techniques. The addition of Cu revealed a high suppression efficiency for the anodic dissolution of stainless steel until 80 degrees C. The ease of passivation of stainless steel was sensitive to Cu content in the matrix and pH and temperature of solution. A second anodic current maximum (I-a2) was observed at -10 (+/-10) mV (see) In the anodic curve of stainless steels containing Cu, exhibiting active-passive transition, and its value depended on the amount of Cu layer accumulated on the surface irrespective of Cu content in the matrix. A negative current loop due to the cathodic reduction of H+ ion was found in more severe dissolution condition of stainless steels containing Cu at potential region preceding I-a2. The second anodic current peak was related to the oxidation of H-adsorbed atom on the surface layer enriched by more noble elements. The action mechanism of Cu addition on corrosion resistance of stainless steel in acid solution was discussed.