Manganese dioxide electrode shows reversible charge storage capacity, if the charge–discharge process is limited to 0.3e− exchange. Addition of small amount of Bi2O3 to manganese dioxide induces reversibility with an exchange of 2e−/Mn. Nickel hydroxide is known to reversibly exchange 1e−. In spite of isostructural relationship between the cobalt hydroxide, nickel hydroxide and manganese dioxide, cobalt hydroxide does not show any electrochemical activity. Bi2O3 modified cobalt hydroxide electrodes exchanges 0.3–0.5e−/Co during the charge discharge process. The oxidation–reduction process in cobalt hydroxide and Bi2O3 modified cobalt hydroxide electrodes were monitored using the PXRD patterns.