Nickel hydroxide is widely used as the active material in positive electrodes of rechargeable alkaline batteries. In this paper, the effects of cupric oxide additive on the characteristics of the nickel electrode have been investigated. The results indicate that the addition of cupric oxide in the nickel electrode can prevent swelling of the nickel electrode during charging and thus prolong the cycle-life of rechargeable batteries. Cupric oxide additive can also promote the transformation from cobalt powder to beta-CoOOH and make cobalt additive be well-spread on nickel hydroxide particles, thus facilitate the charging process in the initial stage.