Improvement of hydrogen capacity in hydrogen-absorbing alloys has been achieved in recent years. Mg-based alloys which were synthesized by ball milling showed lower dehydrogenation temperatures than intermetallic Mg-based alloys. This technique is also effective for preparing a novel Mg-based amorphous alloy, MgNi, and its hydride. Besides conventional intermetallic compounds such as LaNi5, solid solution alloy, 'Laves phase related BCC solid solution' with body-centered-cubic structure showed a hydrogen capacity of 2.2 mass% at room temperature. Alanate, which is not an interstitial hydride, was found to react with gaseous hydrogen reversibly with a catalyst, and its hydrogen capacity was more than 3 mass%. (C) 1999 Elsevier Science Ltd. All rights reserved.