A process for producing hydrogen for direct use as a fuel or for input to a fuel cell from dissociating H.sub.2O in a plasma reformer with hydrocarbon fuel acting as an initiator. The molar ratio of water to hydrocarbon fuel in the input mixture for reactions, and therefore the production of hydrogen from water, increases with the carbon number of the hydrocarbon fuel. Steps in the process include: mixing and vaporizing an H.sub.2O and hydrocarbon fuel mixture in an atomization/evaporation chamber, further heating the mixture in a rotating-flow buffer chamber, dissociating H.sub.2O and hydrocarbon fuel in a plasma reformer, converting carbon monoxide and H.sub.2O to hydrogen and carbon dioxide in a water shift reactor and optionally conditioning the reformate stream by removing carbon dioxide and by purifying hydrogen.