We report the electrochemical formation of Pt particles on fluorine-doped tin oxide electrodes by varying the concentration of PtCl42- ions and the overpotentials within the mass-transfer-limited region. The nucleation mechanisms are considered based on the results obtained by cyclic voltammetry, chronoamperometry, and scanning electron microscopy, the nucleation mechanism changes from progressive to instantaneous as the overpotential and the concentration increase. The physical properties of deposited Pt particles, such as particle density, size, and morphology, are also studied with the changes in overpotential, concentration of PtCl42- ions, or both (C) 2010 Elsevier Ltd. All rights reserved