Abstract: An apparatus for generating hydrogen from a controllable water-split reaction. The reaction utilizes a consolidated mass of reactant material, comprising aluminum and a metal oxide initiator, and preferably a water soluble salt catalyst that causes progressive pitting of the aluminum during the reaction. The reactant materials are in particulate form, and are contained within a layer of filter material that allows the water to enter and the hydrogen gas to escape. Water is fed into the mass in a progressive fashion, from one end towards the other. The produced hydrogen is collected and supplied to a fuel cell or other user device. The mass of reactant material may be contained in a replaceable cartridge.