The corrosion behaviour of Sn-3Ag-3Cu (at%) alloy was investigated in 0.1 M NaCl solution by potentiodynamic polarization and impedance spectroscopy measurements and compared with that of the Sn-3Ag-0.5Cu (at%) solder employed in the packaging of some microelectronic components and devices. Scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were used to characterize the samples prior to and after the electrochemical tests. Results showed that in NaCl solution the corrosion resistance of the Sn-3Ag-3Cu alloy was better than that of the Sn-3Ag-0.5Cu solder. The presence of tin oxychlorides or oxyhydroxychlorides was detected at the surface of both alloys investigated after the electrochemical tests. The better corrosion behaviour of the Sn-3Ag-3Cu alloy compared to the Sn-3Ag-0.5Cu solder can be ascribed to a more adherent and compact corrosion products layer. (C) 2009 Elsevier Ltd. All rights reserved.