MgNi x(x=0 5,1 0,1 25,1 5,2 0)binary alloys have been synthesized using mechanical alloying(MA). The effect of nickel on the structure and electrochemical properties of MA Mg Ni binary alloys has been investigated. All MA MgNi x(x=1 0,1 25,1 5,2 0) alloys, except MgNi 0 5 are amorphous. The properties of the amorphous alloys are better than those of the crystallite one. As the nickel content in amorphous alloys increases, the maximum discharge capacity decreases and the average potential moves towards negative direction, but the decay of charge discharge capacity decreases.