Electrochemical oxidation of the surface of a thin gold film overlaid on an optical waveguide and placed in a cell containing sulfuric acid is monitored by integrated optical surface plasmon resonance (IOSPR) combined with cyclic voltammetry. Waveguide transmittance correlates well with the charge transferred to and from the electrode to oxidize and reduce the surface, with a 60% reduction in transmittance being observed for complete formation of the surface oxide. IOSPR sensors combined with electrochemical measurement and control show potential for sensitive and robust integrated multisensors for electroactive species.