Sodium hexanoate is proposed as corrosion inhibitor for copper when the metal is situated in an aggressive aqueous or gaseous environment. The efficiency of the inhibitor, measured by electrochemical techniques in the ASTM 1384 standard solution, depends on the hexanoate concentration. Copper foils immersed in a (0.1 M) sodium hexanoate conditioning bath, and later exposed to a strongly oxidizing gliding arc plasma in humid air, yield oxide layers, the thickness and the nature of which differ from the unconditioned samples since the voltammograms show no CuO at the surface. The organic salt thus limits the oxidation process induced by the gaseous species. The organic layer remains active for at least 30 min. For longer exposures, the salt begins to degrade to carbon dioxide, which makes the plasma treatment a useful tool to clean metallic surfaces.