Surface alloying of Si into AISI 310 austenitic stainless steel (SS) to increase its high temperature corrosion resistance was attempted by employing pack cementation process. High temperature corrosion resistances of AISI 310 SS with or without siliconization treatment were evaluated in air and in CO/CO2 gas mixtures at 700, 750 and 800 degrees C. The experimental results showed that the weight losses for both 310 SS and siliconized 310 SS in CO/CO2=10/1 reducing gas environment were less than those in air atmosphere at the temperatures tested. Furthermore, siliconization treatment provided better high temperature corrosion resistance for 310 SS both in air and in reducing gas environment. Compositional and structural analyses showed that the oxides formed on 310 stainless steel were composed of an outer spinel of Cr/Mn/Fe oxide and an inner layer of chromium oxide in air and reducing gas environments. For siliconized stainless steel, SiO2 was found in the oxide layer after high temperature exposure in the gas environments tested. (C)2000 Elsevier Science S.A. All rights reserved.