The oscillatory reduction of S2O82- ions on the Au(110) electrode in dilute solutions of NaF at potentials positive to the known value of the potential of zero charge (PZC) has been studied. Experimental results based on cyclic voltammetry with rotating disk electrodes and potentiostatic current transients indicate that in the course of S2O82- reduction the surface state of the electrode is modified. It is proposed that the point of zero charge shifts to a more positive potential, and that the oscillatory S2O82- reduction is governed by the Frumkin effect.