Spherical Al-substituted alpha-Ni(OH)(2) for alkaline rechargeable batteries was prepared by a complexation-coprecipitation method. The morphology and structure of the samples were characterized by SEM, XRD and Raman spectroscopy. Their electrochemical performance including charge-discharge behavior, diffusion coefficient of proton (DH+), stability in strong alkaline solution and cycle life was also investigated. The results showed that the M-substituted alpha-Ni(OH)(2) prepared by this method manifests perfect spherical shape and the specific when the pH value of synthesis solution is 11.75. The interlayer discharge capacity of the sample with 18.3 mol% Al reaches 477 mAh g(-1) distance, the oxygen evolution potential and the half discharge potential of the sample increase greatly with the increase of Al content. Compared with beta-Ni(OH)(2) without Al substitution, there are large amounts of proton defects in Al-substituted alpha-Ni(OH)(2) which increases the diffusion coefficient of proton (DH+) measured by current pulse relaxation (CPR). The Al-substituted alpha-Ni(OH)(2) sample shows an excellent structural stability during ageing treatment in 6 M KOH solution and the loss of Al can be neglected. (c) 2004 Elsevier B.V. All rights reserved.