Chronopotentiometry is applied to investigate ion transfer through heterogeneous MA-41 and homogeneous AMX anion exchange membranes in 0.01 and 0.1 M NaCl solutions. The shape of chronopotentiograms depends on the membrane resistance, heterogeneity of the membrane surface, the hydrodynamic conditions and the membrane position in the gravitational field of the earth. The data of chronopotentiograms are compared with that obtained by voltamperometry method. It is shown that the transition time is lower in the MA-41 membrane system because of higher local current density through well-conducting regions. The gravitational convection is the main mechanism of the coupled convection enhancing the salt transfer in the 0.1 M NaCl system, while the electro-convection is important in the 0.01 M NaCl system. (C) 2003 Elsevier B.V. All rights reserved.