Under partial charge-discharge cycling conditions at a state of charge (SOC) of 50-70%,. a greater effect on the suppression of the memory effect, which occurs in rechargeable alkaline batteries containing a Ni-electrode, was observed using conductive materials such as nano-sized Co(OH)(2) and CoO powders in the Ni-electrode. The nano-sized Co(OH)(2) powder, prepared by the reverse micelle method, consisted of approximately 15-60 nm spherical-shaped particles. The Ni-Cd cells containing approximately 15- or 20-nm-sized Co(OH)(2) powder and 18 nm CoO powder in the Ni-electrode did not show any memory effect after a 150-cycle partial charge-discharge cycling test, and gamma-NiOOH, which is mainly the origin of the memory effect, was not detected in the Ni-electrode, whereas the Ni-Cd cell containing the same content of 500 nm Co(OH)(2) powder and 18 nm CoO in the Ni-electrode showed the memory effect. The nano-sized Co(OH)(2) powder could be more homogeneously dispersed in the Ni-electrode when compared to the 500 nm powders and might develop a superior electro-conductive network between the Ni(OH)(2) particles. (c) 2008 Elsevier Ltd. All rights reserved.