NOVELTY - Hydrocarbon fuel is converted to hydrogen and carbon monoxide as main reaction products by providing reactor (16) having reactor shell (20) and catalytic structure (34), feeding gas mixture, maintaining catalytic reaction zone (22) at temperature to convert the feed gas mixture, and cooling pre-reaction zone (24) to maintain temperature of feed gas mixture below its flash point.    USE - Used in the conversion of hydrocarbon fuel to hydrogen and carbon monoxide as main reaction products, preferably for producing syngas as fuel for fuel cells to produce electric power (claimed).    ADVANTAGE - The invention provides thermal management of the process in the pre-reaction and post reaction zones of the reactor that enhances yields and reduces carbon deposition.    DETAILED DESCRIPTION - The conversion of hydrocarbon fuel to hydrogen and carbon monoxide as main reaction products involves providing reactor having (a) reactor shell having inlet and outlet and forming a reaction flow passage extending from the inlet to the outlet, the reactor shell also forming a catalytic reaction zone between the inlet and outlet, a pre-reaction zone upstream of the catalytic reaction zone, and a post-reaction zone (26) downstream of the catalytic reaction zone, and (b) catalytic structure disposed in the reaction zone comprising an oxidation catalyst supported on an open-channel support; feeding gas mixture comprising oxygen containing gas and hydrocarbon fuel through the inlet, along the reaction flow passage, and through the catalytic structure; maintaining the catalytic reaction zone at temperature to convert the feed gas mixture to an exit gas stream containing hydrogen and carbon monoxide as main reaction products; and cooling the pre-reaction zone to maintain temperature of feed gas mixture below its flash point until it enters the catalytic reaction zone.    INDEPENDENT CLAIMS are also included for:    (1) a reactor for converting hydrocarbon fuel to hydrocarbon and carbon monoxide as main reaction products comprising the reactor shell, catalytic structure, and cooling mechanism (32) for cooling the pre-reaction zone adjacent the catalytic reaction zone to maintain the temperature of the feed gas mixture below its flash point; and    (2) a system for producing electric power comprising the above reactor, and a fuel cell disposed for receiving the exit gas stream and consuming the hydrogen to produce electric power.    DESCRIPTION OF DRAWING(S) - The figure is a schematic diagram of the reactor.    Reactor (16)    Reactor shell (20)    Catalytic reaction zone (22)    Pre-reaction zone (24)    Post-reaction zone (26)    Fuel inlet (28)    Air inlet (30)    Cooling device (32)    Catalytic structure (34)    Oxidation catalyst (36)    Steam reforming catalyst (38)    Heating mechanism (40)    Radiation shields (42, 44)    Insulation (46)    Product gas (48)