As a part of the development of a gasoline processor for integration with a proton-exchanged membrane (PEM) fuel cell, we carried out the POX reforming reaction of iso-octane, toluene and gasoline over a commercial methane reforming catalyst, and investigated the reaction conditions required to prevent the formation of carbon and the effect of fuel constituents and sulfur impurities in gasoline. The H2 and CO compositions increased with increasing reaction temperature, while those of CO2 and CH4 decreased. It is desirable to maintain an O/C molar ratio of more than 0.6 and an H2O/C molar ratio of 1.5 to 2.0 for vehicle applications. It has been found that carbon formation in the POX reforming of iso-octane occurs below 620 ℃, whereas in the case of toluene it occurs below 640 ℃. POX reforming of gasoline constituents led to the conclusion that hydrogen production is directly related to the constituents of fuels and the operating conditions. It was also found that the coke formation on the surface of catalysts is promoted by sulfur impurities in fuels. For the integration of a fuel processor with PEM fuel cell, studies are needed on the development of new high-performance transition metal-based catalysts with sulfur- and coke-resistance and the desulfurization of fuels before applying the POX reformer based on gasoline feed.