A method is provided in which stoichiometrically proportions of solid
alkali metal borohydride are reacted with solid hydrated alkali metal
borate. Upon heating, the borohydride hydrolyzes to generate controlled
amounts of hydrogen gas and solid by-products. Water for the reaction is
stored and carried in the hydrated borate, which is a hydrate of the
reaction's by-product. At a suitable temperature, the hydrate melts and
releases sufficient water for hydrolysis of the borohydride to molecular
hydrogen.