The effects of aluminium additions on the performance of Ti 2 Ni hydrogen storage alloy electrodes have been studied in the present work. The charge/discharge cycles of the electrodes revealed that the cycle life of the Ti 2 Ni electrodes greatly increases with increasing addition of aluminium. However, the specific capacity of the electrode severely decreases with increasing aluminium content. X-Ray diffraction analysis of the alloy with aluminium addition has indicated that a new phase, Ti 2 Al, was formed during alloy melting and co-existed with Ti 2 Ni. Electrochemical measurements and Auger electron spectroscopy analysis have further shown that the passivity of the new Ti 2 Al phase is responsible for the passivity of the electrode and consequently the cycle life increase of the electrode. The passivity of the electrode is also believed to be one of the reasons responsible for the specific capacity decrease of the electrodes with added aluminium.