Most electrochemical measurements and characterizations rely on a three-electrode system to obtain useful information. Nevertheless, useful information can still be obtained with a two-electrode system when electrochemical measurements done with a three-electrode system become difficult or impossible. For example, cyclic voltammetry performing on an electrochromic device (ECD) at low scanning rates was proposed as a means to determine the limits of the safe operating voltage. In this study, voltammograms in a typical two-electrode cell is simulated digitally. It was found from the numerical simulation that the voltammograms of the cell could provide 'fingerprints' of an ECD. These fingerprints agree well with our earlier experimental observation that the cell characteristics an governed by the electrode with a lower charge capacity. To illustrate the validity of the simulation, complementary electrochromic system comprising the tungsten oxide-polyaniline pair will be discussed. Useful criteria for cell design are also presented.