Nb addition was found to be beneficial to the electrode properties of mechanically alloyed Mg2Ni-based product in 6M KOH solution. Formation of Mg2Ni-based nanocrystalites occurred after 15 and 5h of milling using the initial binary and ternary powder mixtures with stoichiometric compositions of Mg2Ni and Mg1.75Nb0.25Ni, respectively. Further milling of the ternary mixture resulted in the formation of an amorphous phase which became dominant after 30h. Negative electrode made from ternary product after 20h of milling exhibited the highest initial discharge capacity and the longest discharge life. This electrode showed to have a microstructure consisting of nanocrystalline Mg2Ni and an amorphous phase.