Several copper corrosion inhibitors were tested including benzotriazole (BTA), thiourea, potassium ethyl xanthate (KEtX), octadecyl mercaptan, and Bricorr-288((R)). The corrosion breakdown potentials were evaluated using the electrochemical quartz crystal nanobalance (EQCN) technique, by recording linear potential scan voltammetric (i-E) and piezogravimetric (in-E) characteristics. Effects of single inhibitors and their mixtures on the value of the breakdown potential were investigated. Previously found synergistic effects for a mixture of BTA + KEtX and a mixture of TU + KEtX inhibitors were confirmed. The most effective among the copper corrosion inhibitors tested appeared to be Bricorr-288. The representative inhibitor films were subsequently tested using the quartz crystal immittance (QCI) technique. New equations based on experimental admittance data were derived to characterize the film acoustic resistance and the resonator parallel capacitance. On the basis of these equations, a new procedure to evaluate passive elements of the equivalent BVD electrical circuit, has been proposed. A decrease in the admittance maximum, appearing near the resonance frequency, was observed for octadecyl mercaptan and Bricorr-288 films on copper.