Single pulse voltammetry (SPV) has been applied to the study of a charge transfer reaction at a static mercury drop electrode (SMDE) under constant sphericity conditions. Amalgam formation for both a reversible and a slow electrode process has been considered. The use of constant sphericity allows us, on the one hand, to discriminate between kinetic and curvature effects and, on the other, to reduce the undesirable effects from the uncompensated IR drop. Methods for determining heterogeneous kinetic parameters are also proposed and experimental examples of fast and slow electrode processes under constant sphericity conditions in normal pulse voltammetry (NPV) are presented. (C) 2004 Elsevier B.V. All rights reserved.