Oxygen evolution reaction was studied in alkaline medium on a nickel hydroxide electrode modified by electroless cobalt coating. The presence of cobalt coating at the surface of nickel hydroxide can increase the oxygen evolution overpotential promoting full charge of the electrode. It has been found that the oxygen evolution potential at this kind of electrode was apparently higher than that on the nickel hydroxide electrode added with cobalt powder as a conductor. Kinetic studies have also shown that this kind of electrode has a greater Tafel slope for oxygen evolution reaction. The mechanism of oxygen evolution has also been discussed. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.