A new methodology for the electrochemical characterization of any device constituted by two electroactive films of conducting polymers, such as electrochromic windows, artificial muscles, polymeric batteries or supercapacitors, is proposed. During electrochemical characterization of dual polymer devices, the charge consumed by the device and the independent potential evolution vs. a reference electrode (oxidation states) of the two constituent materials are followed. The charges consumed inside and outside the electrochromic potential window of each polymer are measured, therefore obtaining percentages of efficient and inefficient charge. Dual polymer electrochromic systems were constructed and characterized by potential sweeps. The influence of the applied potential limits, the redox charge ratio between the two constituting films, or the starting oxidation state of each material on the final percentage of efficient charge consumed by each electrode were studied. (C) 2007 Elsevier B.V. All rights reserved.