The relationship between dissolution and loss of the electrochemically active surface area (ECA) of Pt nanoparticles under potential cycling was investigated in a 0.5 M H(2)SO(4) solution at 298 K. The nanoparticles were prepared on an Au electrode by electrodeposition in a 40 mM H(2)PtCl(6) solution. Potential cycling was performed for 300 cycles in two different potential ranges: 0.0-1.0 V and 0.0-1.4 V. In both the potential ranges, ECA exhibited rapid loss during the first 100 cycles, but there were no significant changes in Pt dissolution. Pt dissolution was significantly enhanced by shifting the upper potential limit from 1.0 to 1.4 V. but ECA was not affected. On the basis of this result, it is expected that ECA loss was mainly due to agglomeration of Pt rather than electrochemical Ostwald ripening. (C) 2011 Elsevier B.V. All rights reserved.