A technique for the determination of the rate of corrosion is described based on the harmonic analysis of the current of the electrode perturbed with relatively small amplitude undistorted sinusoidal alternating voltage. The measurement carried out in the vicinity of the corrosion potential permits the determination of both the corrosion current density and the Tafel slopes. The technique is illustrated using a study of the corrosion of various types of iron electrodes in acidic and neutral media.