Electronic properties of metals are very important for electrochemical processes occurring at the metal/electrolyte interface [1]. One of the main parameters of solid metals reflecting their electronic structures is the conductivity or the electric resistance. However, when working with bulky electrodes, it is practically impossible to detect variations in the conductivity caused by processes on their surfaces. Quite different conditions take place in the case of thin metal films (<1 ~tm). Shimizu [2] was among the first to suggest measuring the resistance of thin films in electrochemical systems. The conductivity of a thin-film electrode (TFE) is usually measured using ac or dc passed along the electrode [3]. In [4], the method of modulation resistometry was described for the first time, but the experimental data were not interpreted.