Amorphous Mg-based alloy Mg63Ni27Nd10 was prepared by melt-spinning. The phase structures and the electrochemical properties of the ribbons before and after charge/discharge cycling were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) analysis and galvanotactic charge–discharge cycle test, respectively. It was found that the amorphous structure begins to crystallize after four cycles of hydrogenation/dehydrogenation and a new nano-crystallized phase NdMg2Ni9 was detected with average grain size in the range 5–10nm. A good cycle life and high discharge capacity were also observed in the Mg63Ni27Nd10 alloy electrode. The highest discharge capacity reached 580.5mAhg−1 at the discharge current densities of 50mAg−1. It is suggested that homogeneous microstructure contributes to the enhancement in electrochemical characteristics, the presence of NdMg2Ni9 being beneficial for the improvement in cycle life of Mg63Ni27Nd10 alloy electrode.