The effects of partial substitution of nickel by copper in Mg50Ni50 amorphous electrode on itselectrochemical properties have been investigated. Results show that the electrochemical capacity of the alloyis decreased while the cycling life is enhanced after substitution.Analysis on electrode potential shows that theNi atoms in the alloy are partially oxidized while the Cu atoms remains in metallic state during theelectrochemical cycling.After partial substitution of nickel by copper, the electric conductivity along the alloypartials are enhanced,and the whole amounts of the metallic Cu and Ni, which have catalystic effect onhydrogen charge / discharge procedure,are increased.Thus the cycling stability of the alloy is improved. Butthe initial capacity (also maximum capacity) of the alloy decreases for the catalystic effect of Cu being lowerthan Ni.