Specimens of duplex stainless steel UNS S32304 immersed in distilled water were worn under sliding friction conditions. The electrochemical microcell technique and local Auger spectroscopy were then applied to these heterogeneous surfaces to determine the influence of surface chemical composition and surface defects on the electrochemical behavior of each phase of the stainless steel in and out of the wear track. Experiments were performed both in 1 M NaCl, pH 3 (where the passive film is stable), and 0.5 M HCl (where an active peak is observed). In addition, the scanning vibrating electrode technique was combined with a modified microcell to study microgalvanic processes between the surrounding passive surface and the track at the OCP value. (C) 2008 The Electrochemical Society.