The surface coordination chemistry of benzotriazole (BTAH) on a Cu electrode was investigated by electrochemical synthesis of surface complexes and in situ electrochemical surface-enhanced Raman spectroscopy (SERS) in nonaqueous solution. Two different surface complexes were prepared in solution with or without triphenylphosphane (PPh 3 ). A new mixed-valence Cu-N cluster compound containing BTAH was synthesized by direct electrochemical oxidation of Cu in nonaqueous solutions with