MgNi-carbon nanotube composites were prepared by ballmilling the MgNi alloy and multiwalled carbon nanotubes (CNTs, 10 wt %) at various periods of time. It was confirmed by scanning electron microscope images that the MgNi alloy surface was modified by shorter and broken CNTs. The MgNi-CNT composites prepared by ballmilling after 60 min were found to show improved electrochemical properties with respect to the original MgNi alloy. In particular, the discharge capacity of the composite electrode increased from 400 to 480 mAh/g by surface modification with CNTs. The electrochemical reaction activity of the composite electrode was improved as confirmed by cyclic voltammogram. The analysis of the electrochemical impedance spectra showed that the double layer capacitance of the composite electrode increased under steady-state condition, which related to surface area of the particles. On the contrary, however, the improvement of the electrode cycle life was unsatisfactory, which probably attributed to the further generation of a new MgNi-CNT interface.