The performance of a catalytic incinerator depends on the nature of the compounds being oxidized and cannot be predicted simply by knowing the performance of the incinerator with pure-component model compounds. Considering the importance of "mixture effects", an attempt was made to develop a combined model to predict the conversion when benzene and methyl tert-butyl ether (MTBE) are simultaneously oxidized. Complete catalytic oxidation of benzene and MTBE, singly and in mixtures, was investigated over a platinum catalyst. No inhibition effects were seen with benzene, but MTBE conversion was distinctly inhibited by benzene. A Mars-van Krevelen rate model was used to explain the results. Model parameters were obtained from pure-component experiments and then incorporated into a multicomponent model without any adjustment or additional rate parameters. The multicomponent model was able to predict the conversion of benzene and MTBE oxidation in the binary mixture using the pure-component data without adjustable parameters.