The mechanism for the electrode process that occurs on a molybdenum substrate in LiCl-KCl-PbCl2 and LiCl-KCl-PbCl2-PbO melts depending on the concentration of PbO was investigated over the temperature range of 723-823 K using stationary polarization curves and voltammetry techniques. An increase in the concentration of PbO was found to decrease the diffusion-limiting current density for the recovery of lead, which was identified by the appearance of an additional peak in the voltammograms; it can be explained by a decrease in the concentration of Pb2+ ions decrease due to the formation of Pb2O2+ complex ions in the electrolyte. The evaluation of the equilibrium constant K-E and the rate constant of the reaction suggests that this reaction is strongly shifted toward the formation of the Pb2O2+ complex ions. A theoretical polarization curve for the diffusion kinetics was calculated. (C) 2014 The Electrochemical Society. All rights reserved.