The hydrolysis reaction of LiBH4 with a stoichiometric amount of water had 5 times the H-2 yield in comparison with that of using water exceeding the stoichiometric amount. The gravimetric and the volumetric hydrogen densities increased with increasing water added (H2O/LiBH4) followed by a decrease. Those densities had maximum values at H2O/LiBH4 = 1.3: gravimetric hydrogen density per unit weight of LiBH4 and H2O is 7.4 wt%, volumetric hydrogen density per unit weight of NaBH4 and H2O is 60 kgH(2)/M. It can be used for a fuel cell uninterrupted power supply. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.