The role of thiourea in the electrooxidation of borohydride is discussed. Cyclic voltammetry experiments showed the selective inhibition of borohydride hydrolysis by thiourea on Pt. The effectiveness of thiourea or any other potential catalytic hydrolysis inhibitor for increasing the specific capacity of borohydride fuel cell anodes is discussed theoretically in terms of two possible reaction pathways. More studies are required by both surface science techniques and fuel cell experiments in order to elucidate the hydrolysis inhibition mechanism and possible longer-term catalyst poisoning by thiourea. (c) 2007 Published by Elsevier Ltd.