Al-substituted alpha-type nickel hydroxides with different interlayer anions (NO(3)(-) or SO(4)(2)-) have been synthesized by chemical coprecipitation method. The microstructure and morphology of the prepared samples were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscope (SEM). The effect of interlayer anions on the electrochemical performance of the prepared nickel hydroxides were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge/discharge tests. The results demonstrated that the Al-substituted a-type nickel hydroxide with interlayer NO has better electrochemical performance, such as better reaction reversibility, higher proton diffuse coefficient, lower electrochemical impedance, higher specific capacity, and better cyclic stability, than that of the Al-substituted a-type nickel hydroxide with interlayer (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.