Substituting Al for part of Cr in Ti0.32Cr0.43V0.25 alloy caused BCC lattice parameter and crystallite size to increase and lattice strain to decrease. These microstructual changes caused the decrease in the hydrogen storage capacity and the increase in both the plateau pressure and the hysteresis. The results were contradictory to the general observation that the plateau pressure decreases with the increase in the lattice parameter. The fact that the bond structure between H and Al and that between H and the transition metals differ can account for this discrepancy. This difference also resulted in the decrease in the hydrogen storage capacity. The increased hysteresis resulting from the increase in the Al content can be ascribed to the increased crystallite size and the decreased lattice strain. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.