The degradation mechanisms of the Ti-V-based multiphase hydrogen storage electrode alloy (Ti0.8Zr0.2)(V0.533Mn0.107Cr0.16 Ni-0.2)(2) during electrochemical cycling in alkaline electrolyte have been studied systematically by using XRD, SEM, XPS, AES and EIS measurements. The results show that the irreversible hydrogen absorbed in the alloy increases with cycling. The pulverization and oxidation/corrosion of the alloy during cycling are two main factors responsible for the fast degradation of the electrode. It was found that a passive Ti oxide film formed on the alloy surface, leading to an increase in charge transfer resistance on the alloy surface and a decrease in exchange current density I-o. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.