Adsorption and desorption of Dinonylphenol Phosphate Ester (DPE), on the surface of a zinc anode in alkaline solution during discharge, have been studied by AC impedance and numerical fitting techniques. The processes were found reversible only during the initial oxidation. The mechanism of the corrosion inhibition caused by the surfactant was investigated and it was found that both the geometrically blocking effect and the increase of hydrogen evolution overpotential might contribute to the reduction of the corrosion rate. The initial potential “dip” during the discharge of an alkaline zinc cell was found to have resulted from surface coverage of the surfactant.