Roasting-leaching-precipitation-calcinations is the conventional way for manufacturing vanadium oxide. Due to the mixing of sodium and ammonium salts in the ammonium precipitation process, a large amount of high concentration ammonia-nitrogen wastewater is produced. In this work, a novel preparation method of low-valent vanadium oxide has been proposed. Using the intermediate product of sodium metavanadate as material, low-valent vanadium oxide was one-step prepared by electroreduction. The sodium hydroxide was meanwhile formed and could be recycled back to the roasting circuit. Current density, temperature, vanadium concentration and alkali concentration were varied to evaluate current efficiency and energy consumption. A maximum current efficiency of 33.5% and a minimum energy consumption of 2700 kWh were obtained under the optimized conditions of temperature 60 degrees C, vanadium concentration 0.2 M, alkali concentration 0.25 M and current density 267 A/m(2). It is a cleaner production method to prepare low-valent vanadium oxide, showing good prospects. (C) 2016 Elsevier B.V. All rights reserved.