The adsorption of ethyl xanthate on copper specimens from moderately alkaline aqueous solutions has been studied combining polarization and X-ray photoelectron spectroscopic data. It was possible to derive structural information about the surface layers originated by either spontaneous adsorption or electrochemical anodization of the metal. Anodization of the metal in ethyl xanthate-containing solutions originates a surface highly resistant to the corrosive attack by chloride ions. XPS data suggest that copper protection is achieved through the growth of a cuprous diethyl dixanthogen layer on the metal in which the oxidation state +1 of copper becomes stabilized.