The results of morphological and electrochemical characterizations of Cu0.8Pt0.2, Cu0.75Pt0.25, and Cu0.71Pt0.29 dealloying in 1 M H2SO4 are presented. The critical potential values for these systems were measured and compared to previously reported results for the Ag-Au system. The differences between the systems are discussed in terms of their relative surface diffusivity values. Based on potential hold data, the dealloying critical potentials for Cu0.8Pt0.2, Cu0.75Pt0.25, and Cu0.71Pt0.29 are 0.565, 0.730, and 0.800 V, respectively, vs a normal hydrogen reference electrode. The critical overpotentials for dealloying in the Cu-Pt system were found to be approximately 100 mV greater than that for similar compositions in the Ag-Au system. (c) 2005 The Electrochemical Society.