An air cathode electrode for the metal-air battery was prepared and characterized. The performance of air electrode composed of KMnO4 catalyst for oxygen reduction reaction was examined by using the linear polarization and AC impedance methods. The surface morphologies of the air electrodes were investigated by SEM. The crystal structure and properties of the air electrodes were examined by XRD. Experimental results reveal that the air cathode electrodes have excellent electrochemical properties. The several preparation factors affecting the electrochemical performances of the air cathode electrodes were also addressed and discussed. The cathode electrode with a low cost catalyst obtained shows a highly potential candidate for application on alkaline metal-air battery or fuel cell systems. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.