The impedance characteristics of a copper disk electrode/sulfuric acid-cupric sulfate interface were investigated and interpreted in terms of equivalent circuit models. A single reaction mechanism, proposed to correspond to the Cu 2+ o Cu § charge transfer, limited deposition rates over a wide current density range at a well-agitated interface. A rate constant of 1.1 • 10 -6 cm/s, a transfer coefficient of 0.5, and a double layer capacitance of 25 jxF/cm 2 were determined from impedance data corresponding to the rate-limiting step. Arrhenius plots yielded an activation energy of 66 kJ/M and a pre-exponential term of approximately 10 ' cm/s. The involvement of a freely diffusing cupric ion in the rate-limiting step was consistent with the observed data, but the possibility of adsorbed species involvement cannot be eliminated. A minor impedance feature, believed to correspond to a relatively fast surface diffusion limited Cu + ~ Cu(O) charge transfer, was observed at low ac frequencies. In quiescent solutions, the observation of a significant Warburg impedance demonstrated that deposition rates became limited by diffusion of cupric ion to the interface.