Cyclic voltametry experiments coupled with electrochemical quartz crystal microbalance (EQCM) measurements showed the corrosion mechanism of electrodeposited copper in presence of chloride ions. The oxidation of copper in acidic solution containing high concentration of Cl-begins with formation of Cu+ ions. The Cu+ concentration at the vicinity of the electrode increasing, the small solubility product of CuCl is then exceeded, leading to a CuCl precipitation on the gold covered quartz crystal used as working electrode. For highest anodic potentials, the oxidation of electrodeposited copper or CuCl precipitate phases could occur. A combination with structural techniques like SEM, EDAX, AFM and DRX gives insight into the morphology and the nature of these CuCl precipitates. (c) 2006 Elsevier Ltd. All rights reserved.