Kinetics of facilitated ion transfer across the interface between water/nitrobenzene and water/1,2-dichloroethane has been studied by normal pulse voltammetry using a micro-interface supported at the tip of a glass capillary. An equation for current response to potential-step signals under spherical diffusion conditions has been derived and applied to the analysis of the voltammograms for transfer of Ba2+, Sr2+ and Na+ facilitated by dibenzo-18-crown-6 (DB18C6) and dibenzo-24-crown-8 (DB24C8). It has been found that the transfers of Ba2+ and Sr2+ facilitated by the crown ethers across water/nitrobenzene interface have formal rate constants of the order of 10(-2) and 10(-3) cm/s, respectively. It has also been found that the formal rate constant for transfer of Na+ is higher than the determinable limit by the method employed. (C) 1998 Elsevier Science Ltd. All rights reserved.