The electrochemical performance of ZrMn0.5V0.4Ni1.1Cox (x = 0.05, 0.1, 0.15, 0.2) system alloys, based on ZrMn0.5V0.4Ni1.1, are investigated intensively. With the increase in Cc content, the maximum capacity, high-rate dischargeability (HRD) and CL of the alloy electrode decreases, and the self-dischargeability increases. Electrochemical activities of ZrMn0.5V0.4Ni1.1Cox alloy electrodes are worse than that of the matrix alloy. While, the alloy electrodes are heat-treated by hot alkaline solutions, their activities improve greatly, and there are not more than four cycles to reach the maximum capacity. However, the maximum capacities show a small decrease. The reversible capacity loss mainly results from desorption of hydrogen from hydride, and is affected by the stability of hydrides. E of ZrMn0.5V0.4Ni1.1Cox alloy electrodes agrees well with their reversible capacity loss. In all the investigated alloy electrodes, ZrMn0.5V0.4Ni1.1Co0.05 alloy electrode has the most excellent properties in capacity, CL, HRD and self-dischargeability. ZrMn0.5V0.4Ni1.1Co0.05 alloy is a favorable alloy for use as an active electrode if its temperature property will be improved.