NOVELTY - The method comprises heating water (14) to superheated steam, mixing a hydrocarbon fuel (12) with the steam to produce a fuel/steam mixture, flowing the fuel/steam mixture in a gap space between tubular separate surfaces, and heating one of the separate surfaces to maintain a reaction temperature range that induces the water gas shift reaction. The gap space between the separate surfaces is less than 1000 microns. The separate surfaces are curved and concentric, and include an inner surface and an outer surface.    USE - The method is useful for inducing a water gas shift reaction between a hydrocarbon fuel and water for creating hydrogen gas and waste raffinate gases (claimed); where hydrogen gas is useful for a proton exchange membrane fuel cell.    ADVANTAGE - The method ensures efficient inducing the water gas shift reaction between hydrocarbon fuel and water thus rapidly producing the ultra pure hydrogen gas with improved combustion characteristics and high purity (99.999%).    DETAILED DESCRIPTION - The method comprises heating water (14) to superheated steam, mixing a hydrocarbon fuel (12) with the steam to produce a fuel/steam mixture, flowing the fuel/steam mixture in a gap space between tubular separate surfaces, and heating one of the separate surfaces to maintain a reaction temperature range that induces the water gas shift reaction. The gap space between the separate surfaces is less than 1000 microns. The separate surfaces are curved and concentric, and include an inner surface and an outer surface. The step of heating one of the separate surfaces comprises heating the outer surface, exposing the outer surface to combustion gases, and burning some of raffinate gases. The outer surface surrounds with a sleeve. The combustion gases flow between the outer surface and the sleeve. The step of heating the water to superheated steam comprises transferring heat from the hydrogen gas and the raffinate gases to water to produce superheated steam. INDEPENDENT CLAIMS are included for:    (1) a method of producing hydrogen gas from a supply of hydrocarbon fuel; and    (2) a method of operating a steam reformer for inducing a water gas shift reaction between steam and a hydrocarbon.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a fuel processor system with a fuel cell.    Fuel processor system (10)    Hydrocarbon fuel (12)    Water (14)    Fuel cell (16)    Initial heat exchanger (18)    Multi-channel steam reformer. (20)