New electrochemical investigations of the Pb/PbO2/PbSO4 electrode are reported. In this study we focus on two related phenomena: an anodic peak that appears on cathodic sweep, which we regard as a reactivation peak and a voltage dip that appears in galvanostatic discharges, commonly known as "coup de fouet". It was possible to demonstrate that the commonly accepted interpretation for the "coup de fouet" as PbSO4 nucleation over PbO2 surface is incorrect. From the comparison between galvanostatic and voltammetric experiments, the connection between the "coup de fouet" and the reactivation peak is elucidated and a model that explains the overall behavior is proposed. (C) 2004 Elsevier B.V. All rights reserved.