NOVELTY - A hydrogen gas generator comprises a reaction chamber for receiving a solid reactant having a reaction product separator impermeable to solid reactant and a spring for biasing reactant products against the separator; a liquid reactant dispenser to store a liquid reactant and fluidly coupled to the chamber, such that dispensed liquid reactant reacts with solid reactant to produce hydrogen gas and a waste product that are permeable through the separator; and a product collector coupled to chamber to collect hydrogen gas and waste product.    USE - For generating hydrogen gas (claimed), which is useful as fuel for fuel cell system; useful as hydrogen generating fuel cartridge for fuel cell system.    ADVANTAGE - The hydrogen gas generator is portable. The hydrogen gas generator has a design that facilitates the hydrogen producing reactions, as a portion of the solid is continuously exposed to the liquid reactant, since the biasing force provided by the spring forces the gaseous, liquid and small particulate products of the reaction through the separator screen. This prevents the products of the reaction from coating the solid reactant, and from mixing with the liquid reactant. By locating certain pumping components, i.e. nitinol wire, plunger head, plunger outside of the fuel cartridge, the manufacturing cost of the cartridge is reduced. By sealing the pumping chamber with the diaphragm, the citric acid solution is not permitted to leave the fuel cartridge, and thus minimizing the likelihood of damage or harm caused by acid leakage. The only fluid that is permitted to leave the fuel cartridge is hydrogen gas, via port. The design of hydrogen gas generator provides the simplified control of gas generation. Since hydrogen gas is generated only when the citric acid solution is mixed with the solid sodium borohydride, the rate of pumping entirely controls the rate of hydrogen gas production.    DETAILED DESCRIPTION - A hydrogen gas generator comprises a reaction chamber for receiving a solid reactant having a reaction product separator impermeable to solid reactant and a spring for biasing reactant products against the separator; a liquid reactant dispenser for storing a liquid reactant and fluidly coupled to reaction chamber, such that dispensed liquid reactant reacts with the solid reactant in the reaction chamber to produce hydrogen gas and a waste product that are permeable through the separator; and a product collector coupled to the reaction chamber for collecting hydrogen gas and waste product that have passed through the separator. The hydrogen gas generator further comprises a hydrogen gas separator located in the product collector and which is permeable to hydrogen gas and impermeable to the waste product.    An INDEPENDENT CLAIM is included for generating hydrogen gas.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of fluid flow inside the hydrogen generating fuel cartridge.