Regulated hydrogen production system

A production system (40, 41, 51, 61, 71, 81, 91, 101) includes a reaction chamber (44) having an inlet (48) and outlet (50), a gas collection chamber (58) coupled with the reaction chamber (44) and a regulator coupled to the gas collection chamber (58). The regulator controls the flow of reactant to the reaction chamber (44) in response to the pressure in the gas collection chamber (58).