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 13603 modified cobalt hydroxide electrodes were monitored using the PXRD patterns. (C) 2008 Elsevier Ltd. All rights reserved.