In the present work, we show that a large interfacial energy gradient is produced at a front of an electrochemical wave appearing in CuSn-alloy oscillatory electrodeposition from an aqueous solution by observing the directional lateral motion of an oil droplet put on an electrode surface. During the oscillation, the surface composition of the electrodeposit changed periodically between Cu-rich and Sn-rich alloys. The transition from the Cu-rich phase to the Sn-rich phase, or vice versa, initiated at a region of the electrode and propagated to the entire surface as an electrochemical wave. Contact angle measurements of the droplet revealed that the electrochemical interfacial energy varies largely between during Cu-rich and Sn-rich alloy electrodeposition. Repetitive approaches of the electrochemical wave front to the droplet drives the directional movement of the droplet, indicating the lateral imbalance of the interfacial energy (i.e., the interfacial tension) at the front is so large that the force produced by the imbalance can transport macroscopic objects such as an oil droplet. (C) 2009 Elsevier Ltd. All rights reserved.