The catalytic combustions of different naturally oxygenated volatile organic compounds (ethyl acetate, isopropanol, methyl ethyl ketone (MEK), and benzyl alcohol) alone and in binary mixtures were investigated over pure gamma-Al2O3, Mn/gamma-Al2O3, and Cr/gamma-Al2O3. The catalysts were prepared by the wet impregnation method and were characterized using XRD, ICP-AES, SEM, and BET. Mn/gamma-Al2O3 showed higher activity than others in combustion of the O-VOCs, whereas complete conversion of isopropanol (the most reactive O-VOC) occurred at 350 degrees C and 400 degrees C on Mn/gamma-Al2O3 and Cr/gamma-Al2O3, respectively. The following order was found for reactivity of organic compounds in single form: isopropanol > benzyl alcohol > ethyl acetate > MEK. There was no relation between activity of the catalyst and BET surface area. An inhibition/promotion effect was found in the oxidation of O-VOC binary mixtures because of the competitive adsorption on the catalyst, leading to an oxidation behavior for O-VOC binary mixtures different than that of single components. The presence of water vapor as a co-feed had an inhibition effect on isopropanol oxidation and was temperature-dependent such that it decreased above 350 degrees C.