The present invention provides an alkaline storage battery which comprises a positive electrode prepared by filling a nickel hydroxide in a porous plaque as an active material, a negative electrode, a separator and an alkaline electrolyte, said positive electrode containing the nickel hydroxide as a main component and a complex oxide of lithium and cobalt as a conductive agent. The lithium-cobalt complex oxide as a conductive agent is preferably represented by the formula Li x CoO 2 (x is 0.2-0.9). A method for treating the surface of the positive electrode active material which comprises the step of forming a coating layer of cobalt hydroxide on nickel hydroxide powders is also disclosed.