A safe, simple, compact process generates high-purity hydrogen gas on demand from base-stabilized, aqueous solutions of sodium borohydride, NaBH4, by using a ruthenium, Ru, catalyst. These NaBH4-based solutions can store up to 7% hydrogen by weight. NaBH4 solutions do not generate significant amounts of H-2 gas under ambient conditions. However, when in contact with Ru catalyst, NaBH4 solutions spontaneously hydrolyze to form H-2 gas and sodium berate, a water-soluble, inert salt. When Ru catalyst is separated from the NaBH4 solution, H-2 generation stops. This H-2 generator promises to be safer, have quicker response to H-2 demand, have a greater H-2 storage efficiency, and be more easily controlled than commonly used H-2 storage devices or generators. Nonflammable NaBH4 solutions can be easily coupled to provide H-2 to internal combustion engines or fuel cell power systems. (C) 2000 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.