Water resistance was imparted to ZrMn2, Mg-10%Ni and Ti-Zr-Fe-Mn alloys by encapsulating hydrided powders with ceramic overlayers derived from alcoxides. The treated powders readily absorbed hydrogen after immersed in water or showed essentially the same hydrogen capacity under a humidified hydrogen atmosphere (partial pressure of water: 0.6 kPa) as that under pure hydrogen. Loss of hydrogen capacity on the encapsulating treatment and/or poor kinetics of absorption and desorption due to coverage of surface are to be resolved prior to practical use of these composite materials. (C) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.