Single particle of nickel hydroxide and the surface-treated one with cobalt element were performed to review the effect of LiOH additive in alkaline electrolyte for Ni-MH batteries using microelectrode test system. As a result of cyclic voltammetry, the electrochemical behaviors such as the oxidation/reduction and oxygen evolution reaction are clearly observed for a single particle of nickel hydroxide, respectively. Furthermore, the reduction current peak of nickel hydroxide added with LiOH in electrolyte was very low and broad compared with the normal nickel hydroxide without an additive LiOH, which had a bad effect to the crystallization structure of nickel hydroxide. However, it was found that capacity and cycle properties of the nickel hydroxide treated with cobalt greatly increased by the addition of LiOH.