The inhibition of Cu corrosion;in 0.1 M NaCl solution was studied using the EQCM technique. Some organic compounds, at 10(-3) M concentration, were tested as inhibitors. The inhibiting effect of these additives was evaluated by recording the anodic and cathodic polarization curves on Cu, electroplated on quartz crystals. At the same time the mass changes of the electrode, as a function of the potential, were recorded. The formation of the protective film during immersion in distilled water or 0.1 M NaCl solution containing the inhibitors was followed by variation of the EQCM frequency. The protective characteristics of these films were evaluated by the mass variations of the electrode immersed in 0.1 M NaCl solution and by the voltammograms recorded after 1 min or 5 h immersion in 0.1 M NaCl solution. FTIR reflection spectra were recorded on Cu sheets immersed for 1 or 60 min in NaCl solution in the presence of inhibitors. They showed a very rapid interaction between metal surface and organic molecule. The results obtained allow us to conclude that EQCM technique has a valuable part to play in the interpretation of corrosion and corrosion inhibition mechanisms.