NOVELTY - A hydrogen-generating apparatus has a vertically aligned reforming reaction zone comprising an oxidation zone; a flow transition zone; radially permeable reaction zones around the vertically aligned reforming reaction zone between the reaction zone base and the insulated reaction zone ceiling; a radial product collection zone; and vertically aligned heat exchanger tubes.    USE - For generating hydrogen from a fuel stream for use in conjunction with a fuel cell for production of electricity, or to drive a transportation vehicle.    ADVANTAGE - The method produces hydrogen in a smaller, simpler and less costly hydrogen plants. It provides a varying amount of hydrogen as demand for electric power from the fuel cell varies.    DETAILED DESCRIPTION - A hydrogen-generating apparatus comprises:    (a) a vertically aligned reforming reaction zone (60) comprising an oxidation zone (14) arranged vertically over a reaction zone base (11);    (b) a flow transition zone (18) to collect an effluent of the oxidation zone, is established by sealingly disposing a reforming catalyst zone radially permeable and surrounding the oxidation zone on the reaction zone base between the reaction zone base and an insulated reaction zone ceiling (13) at a distance from the oxidation zone;    (c) radially permeable reaction zones (24, 26, 28) surrounding the vertically aligned reforming reaction zone arranged sealingly between the reaction zone base and the insulated reaction zone ceiling;    (d) a radial product collection zone (30) arranged sealingly about an outer catalyst zone of the radially permeable catalyst zones; and    (e) vertically aligned heat exchanger tubes (32) arranged in at least one of the radially permeable reaction zones and extending through the reactor zone base and the insulated reaction zone ceiling, the vertically aligned heat exchanger tubes are in fluid communication with an essentially isothermal fluid (54).    The vertically aligned reforming zone is at least partially submerged in the essentially isothermal fluid.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of a fuel processor/boiler.    Inert catalyst zone (12)    Reaction zone base (11)    Insulated reaction zone ceiling (13)    Oxidation zone (14)    Flow transition zone (18)    Radially permeable reaction zones (24, 26, 28)    Radial product collection zone (30)    Heat exchanger tubes (32)    Isothermal fluid (54)    Reforming reaction zone (60)    Boiler vessel (100)