The electrochemical behavior of ammonia borane on an Au electrode in the absence and presence of thiourea (TU) was detailedly investigated by cyclic voltammetry (CV). In the absence of TU, the feature of the CV is fairly complex affected by both the hydrolysis and the direct oxidation of ammonia borane. With the aid of TU, known as an effective inhibitor for the formation and recombination of adsorbed H radicals associated with ammonia borane hydrolysis, the two peaks at 414 and 0 mV may be attributed to direct electrooxidation of ammonia borane at Au electrode. These two peaks are particularly important for the practical direct ammonia borane fuel cell (DABFC). Additionally, the Tafel slope (b=0.15V) and charge transfer coefficient (alpha=0.604) were obtained as well as number of electrons exchanged (n = 2) in the ammonia borane oxidation at the Au/solution interface in the presence of TU. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.