Mass transfer dynamics of an electrochemically produced ferrocenium cation across a single-nitrobenzene-microdroplet / water interface were studied on the basis of micromanipulation and microelectrode methods. Cyclic voltammograms of ferrocene in single droplets were analyzed as a function of a potential sweep rate and a liquid-junction potential between the droplet and water. The interfacial ion transfer processes of the ferrocenium cation are discussed kinetically. (C) 2000 Elsevier Science B.V. All rights reserved.