Electrochemical properties of the ZrNi alloy electrode with the boiling alkaline treatment were investigated. The boiling alkaline treatment was performed by immersing ZrNi powder or electrode in a boiling 6 M KOH aqueous solution for 4 h. During the boiling alkaline treatment, the bulk structure of the ZrNi powder, the B33 -type (CrB) structure, remained, whereas the outer ZrO 2 native surface was replaced by Ni(OH) 2 . The initial discharge capacity at 10 mA g −1 and 333 K for the ZrNi alloy electrode was increased from 18 to 320 mAh g −1 by the boiling alkaline treatment. However, cycle performance got worse, because the ZrNi alloy particles were pulverized for the charge–discharge cycles. [ABSTRACT FROM AUTHOR]