Al-substituted alpha-nickel hydroxide were used as active materials in pasted nickel hydroxide electrodes for rechargeable alkaline batteries. The electrochemical impedance spectra of alpha-nickel hydroxide electrodes with different Al contents were measured. An equivalent circuit model was applied to simulate the experimental results. Some equivalent circuit parameters for different electrodes were determined. The reason why the alpha-nickel hydroxide electrode with 25% Al shows a better performance was discussed using these parameters. (C) 2002 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.