The electrochemical oxidation of 2-mercaptobenzimidazole (MBIH) on a copper substrate in alkaline methanol solution was investigated by cyclic voltammetry, chronoamperommetry, and quartz crystal microbalance. Cyclic voltammograms indicated that the polymer film (pMBIH) is formed anodically and this film cannot be reduced by cathodic potential scan. However, one potential cycle is not sufficient to form a good barrier layer, and the anodic current peak is observed on subsequent cycles, though its height decreases for each cycle. If the film formations were performed at a constant potential, an EQCM showed the adsorption of MBIH before the anodic oxidation of this monomer leading to the film formation. The film forming efficiency was maximum at ca. 0.8 VSCE though the film thickness increased up to 1.2 VSCE. A thicker film was obtained by potential scan method. From a long period impedance measurement, it was shown that the polymer film thus obtained on copper exhibited a high protective effectiveness.