High-temperature oxidation tests were conducted on three commercial carbon steels in simulated combustion environments of natural gas with 99% theoretical air at a total pressure of 1 atm. It was found that 0.2 and 40 ppm sulfur contamination in the environments tended to accelerate the rate of scaling at 1200°C, but slowed it at 1100°C. At 1100°C,the sulfhr was thought to adsorb on the scale surface, blocking the surface mobility and hence partly blocking the access of oxidant molecules to the
surface. However at 1200°C, it was apparent that the retarding effect of the adsorbed sulfiMon the scale surface was lost, and instead surfhce nobilities were enhanced. The oxidation kinetics and mechanisms for the observed results are discussed. Keywords: oxidation, linear kinetics, steel, sulfh.rpoisoning effect, combustion atmosphere.