The effect of NO, SO2 and H2O concentrations on the rate of carbon oxidation with a Pt/SiO2 catalyst and the mechanisms of the reactions were studied. Addition of NO to the reactant gas enhanced the oxidation rate of carbon black. Furthermore, the addition of trace quantities of SO2 (approximately 8 ppm) to the reactant gas containing NO and H2O substantially enhanced the oxidation rate while it had no effect in the absence of NO. Nitrogen dioxide was thought to be an oxidizer that directly attacks the carbon and turns itself into NO. The promotional effect of SO2 was attributed to SO3 (or H2SO4), produced from SO2 over Pt, which may work as a catalyst that accelerates the oxidation of carbon by NO2. H2O may be indispensable as a reactant for hydrolysis involved in this promoted oxidation and reaction.