This paper introduces a novel electrolysis method to prepare NiOOH by oxidizing spherical Ni(OH)(2) in a dilute alkaline solution (pH = 8-13). The effects of preparation conditions, including KCl concentration, pH, constant voltage, temperature and oxidation time, on the synthesis of NiOOH were systematically investigated. The results show that the electrolytic efficiency and reaction rate are superior and the electrolyte can be conveniently re-utilized. The physical properties and electrochemical performance of NiOOH samples were also studied. The results show that the NiOOH, prepared by this electrolysis method, is pure beta phase, even if the electrolysis duration is fully prolonged. The spherical NiOOH sample not only possesses excellent electrochemical activities, providing discharge capacities of 256.5 and 199.1 mAh g(-1), and volume capacities of 625.86 and 485.80 mAh cm(-3) at rates of 0.2 C and 3 C, respectively, but also has the high tap density of 2.44 g cm(-3). Moreover, the synthesis process of the new electrolysis method is environmentally friendly, cost saving, and efficient for a large-scale production. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.