The operating characteristics of catalytic reactors used in systems which generate hydrogen from the contact of a fuel with a catalyst are enhanced by such reactors incorporating one or more of group of elements consisting of (a) a heat exchanging element that preheats the fuel solution prior to its contact with the catalyst, (b) one or more liquid diffusing elements which distributes the flow of fuel over the catalyst so as to increase the generation hydrogen from such contact, (c) multiple catalysts having different hydrogen generating characteristics and d) a membrane capable of operating at pressures equal to or greater than 50 psig which surrounds catalytic material in the reactor and separates the generated hydrogen from the fuel.
