NOVELTY - A hydrogen supply system comprises hydrogen storage unit to store hydrogen, hydride storage unit to store aqueous hydride, reactor coupled to the reactor and hydrogen storage unit, heat exchanger coupled to the reactor, regenerator coupled to the reactor, first and second valves (121, 123), third valve (125), temperature detector, and control unit.    USE - For fuel cell (claimed).    ADVANTAGE - The invention enables the fuel cell to improve ignition performance at a low temperature and decrease hydrogen consumption rate during the ignition. It can increase the cooling water temperature without hydrogen consumption at ignition.    DETAILED DESCRIPTION - Hydrogen supply system comprises hydrogen storage unit to store hydrogen, hydride storage unit to store aqueous hydride, reactor coupled to the reactor and hydrogen storage unit and configured to be supplied with aqueous hydride from the hydride storage unit, heat exchanger coupled to the reactor and configured to be supplied with oxide from the reactor and hydrogen from the hydrogen storage unit, regenerator coupled to the reactor, first valve disposed inline between the hydrogen storage unit and fuel cell stack and configured to control a supply of hydrogen from the hydrogen storage unit the fuel cell stack, second valve disposed inline between the hydrogen storage unit and regenerator and configured to control a supply of hydrogen from the hydrogen storage unit to the regenerator, third valve disposed inline between the heat exchanger and fuel cell stack and configured to control supply of hydrogen from the heat exchanger to the fuel cell stack, temperature detector to detect a temperature of coolant flowing to the fuel cell stack and to generate a corresponding temperature signal, and control unit to generate control signals for actuating the first valve, second valve, and third valve based on the temperature signal from the temperature detector. The reactor is configured to react the supplied aqueous hydride to generate oxide and hydrogen. The regenerator is configured to react the supplied oxide and hydrogen to generate an aqueous hydride.    An INDEPENDENT CLAIM is also included for a method for cooling a hydrogen fuel cell comprising calculating the temperature of coolant flowing to a fuel cell stack, determining that the temperature of the coolant is higher than a predetermined temperature, generating hydrogen and oxide from an aqueous hydride, and exchanging heat contained in the hydrogen with the coolant to raise the temperature of fuel cell stack.    DESCRIPTION OF DRAWING(S) - The figure is a block diagram showing a hydrogen supply system for a fuel cell.    Cooling water pump (115)    First and second valves (121, 123)    Third valve (125)