In the present study, a rotating electrochemical quartz crystal microbalance was used to investigate the effect of lead on the leaching of gold in aerated alkaline cyanide solutions. It was found that the addition of trace amounts of lead substantially increased the leaching rate, and it is believed that the role of lead was to modify the surface of the gold by cementation. Complementary electrochemical studies showed that lead acts in two ways: it reduces the overpotential required for the oxidation of gold and it enhances the reduction of oxygen. Thus, it is likely that bimetallic corrosion was occurring during gold leaching in the presence of lead. The effect of rotation rate, and cyanide and oxygen concentrations were investigated, and it was found that the action of lead was critically dependent on leaching conditions.