Potassium borohydride (KBH4) reacted very slowly with water to liberate 4mol of hydrogen/mol of compound at room temperature. The hydrolysis and stability conditions of KBH4 investigated depend on KBH4 concentrations, concentration of alkaline solutions, temperatures and electrical field intensity. Yield of produced hydrogen by self-hydrolysis of KBH4 increases as the temperature increased and it produced 53.9% yield at the end of 300 min at 60 degrees C. The reaction rate order of hydrolysis of KBH4 in aqueous solution is found at about 0.7-0.8 and the activation energy for hydrolysis is calculated as 14,700 kJ/mol. Potassium borohydride is stable both in room temperature and in aqueous alkaline solution. In this study, the electrical field that is not needed for catalytic activity was used for the hydrolysis of KBH4 aqueous solution. It was found that 6 mol of hydrogen/mol of potassium borohydride was liberated in the presence of electrical field, whereas 4 mol of hydrogen was produced in the absence of electrical field per mol of potassium borohydride. (C) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All fights reserved.