The effects of heavy rare earth oxide additives on the high temperature performance of nickel electrodes were investigated. It is found that the 1 C charge acceptance ability of the spherical Ni(OH)2 electrode with heavy rare earth oxide additive is improved; however, the heavy rare earth oxide as additive has negative effect on the high rate discharge performance at room temperature. The cyclic voltammetry (CV) results indicate that the heavy rare earth oxide as additive can increase the overpotential of oxygen evolution at high temperatures. The oxygen evolution reaction is effectively depressed and leads to the increase of charge efficiency of Ni(OH)2 electrode at high temperatures. Moreover, the reversibility of Ni(OH)2 electrode is also improved at high temperatures.