Expressions for the reaction layer thickness of a catalytic mechanism at planar and spherical electrodes, deduced for transient and stationary chronopotentiometric conditions for three types of programmed currents (constant current, power time current and exponential time current) are presented. From these expressions, the conditions for attaining a stationary behaviour, i.e., a time independent reaction layer thickness, are discussed, and the advantages derived form the use of exponential time currents in order to accelerate the evolution of the response towards its stationary limit are analysed. Finally, expressions for the potential time curves and their reciprocal derivatives are also given and the influence of the reaction layer thickness is studied. (C) 2011 Elsevier B.V. All rights reserved.