Electrodeposition of Ag was studied in several ionic liquids. When the potential applied more negative than -0.25 V vs. Ag l Ag(I), the cathodic current density reached in the diffusion-controlled region. The surface morphology of Ag deposits, the initial stage of nucleation and crystal growth behavior and the apparent current efficiency changed depending on the applied potential. These results indicate that the applied potential affects the electrodeposition processes of Ag under diffusion-controlled region. Since the electrode reaction rate is controlled by diffusion, the change of the surface morphology may be caused by the change of the double layer structure, which is expected to depend on the applied potential. In addition, Ag nanoparticles were obtained in the ionic liquid after potentiostatic cathodic reduction, suggesting a part of reduced Ag was dispersed in the ionic liquid. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3610202] All rights reserved.