Ultrafine Ni(OH)(2) powder is prepared by converting a Ni2C2O4 precipitate in NaOH solution which contained Tween-80. The sample prepared by this method is beta(II)-type phase and its particle size is about 30 nm. The electrochemical behaviour of nickel foam electrodes using this ultrafine Ni(OH)(2) powder as active material is studied and compared with micron-sized spherical Ni(OH)(2) by means of a galvanostatic charge-discharge method, cyclic voltamperommetry (CV) and electrochemical impedance spectroscopy (EIS). It is found that ultrafine Ni(OH)(2) powder has superior electrochemical properties, such as lower polarization, better reversibility, and smaller reaction resistance.