The effect of benzotriazole (BTA) on the open-circuit potential of copper in buffered acid solutions was studied in the absence of the passive Cu(I) BTA film. The film was removed from the surface by in situ continuous scratching of the electrode. At a film-free surface BTA acted mainly as a cathodic inhibitor in contrast to its well-established role as an anodic inhibitor at the film-covered copper surface. The implications for chemical mechanical polishing of copper in BTA-containing slurries are discussed. (C) 2003 The Electrochemical Society.