A theoretical analysis has been conducted to evaluate the effect of migration in galvanostatic processes and to provide a fundamental basis for assessing the limits of applicability of Sand's equation in chronopotentiometric measurements. The results of the computation show that the diffusion potential is a significant driving force for migration transport within the diffusion layer. The square root of the transition time is inversely proportional to the applied current density, irrespective of the degree of migrational interaction in the system. Three case studies are presented to illustrate the effect of migration in different electrochemical processes. © 1988, The Electrochemical Society, Inc. All rights reserved.