This work examines the effect of various hydrocarbons on fuel processor light-off and reforming. Major hydrocarbon fuel constituents, such as aliphatic compounds. napthanes, and aromatics have been compared with the fuel processing performance of blended fuel components and reformulated gasoline to examine synergistic or detrimental effects the fuel components have in a real fuel blend. Short chained aliphatic hydrocarbons tend to have favorable light-off and reforming characteristics for catalytic autothermal reforming compared with longer-chained and aromatic components. Oxygenated hydrocarbons have lower light-off requirements than do pure hydrocarbons. Gas phase oxidation favors higher cetane # fuels, which tend to be longer chained hydrocarbons. Energy consumption during the start-up process shows a large fuel effect. Methanol and dimethylether (DME) show lower start-up energy demands for the fuel processor start-up than do high temperature reforming hydrocarbon fuels such as methane, gasoline and ethanol. Aromatics and longer chained hydrocarbons show a higher tendency for carbon formation, increasing the amount of carbon formed during the light-off phase while the addition of oxygenates tends to lower the carbon formed during the start-up process. (c) 2004 Elsevier B.V. All rights reserved.