The effect of ac-induced current on corrosion of materials was investigated. The corroding system consisting of the polarization resistance, the double-layer capacitance, and the solution resistance was considered under activation control. The nonlinear differential equation voltage that describes the system was linearized and expressions for the steady-state corrosion potential and corrosion current were obtained. The data show that alternating voltage-induced corrosion current increases with lowering of the signal frequency, but it is enhanced by the peak potential. The data also show that inherent corrosion behavior depends upon the Tafel constants and the dc corrosion current, but it is independent of the dc corrosion potential. (c) 2007 The Electrochemical Society.