Polyaniline (PANI)/copper oxide (CuO), poly(3,4-ethylenedioxythiophene) (PEDOT)/CuO and polypyrrole (PPy)/CuO have been synthesized electrochemically on glassy carbon electrode in sodium dodecyl sulfate in sulfuric acid solution as an electroactive material. To our best knowledge, the first report on comparison of supercapacitor behaviors of PANI/CuO, PEDOT/CuO and PPy/CuO nanocomposite films was studied by electrochemical impedance spectroscopy, related to the plots of Nyquist, Bode magnitude and Bode phase. The highest specific capacitance (C (sp)) was obtained as C (sp) = 286.35 F x g(-1) at the scan rate of 20 mV x s(-1) for PANI/CuO amongst the PEDOT/CuO (C (sp) = 198.89 F x g(-1) at 5 mV x s(-1)) and PPy/CuO (C (sp) = 20.78 F x g(-1) at 5 mV x s(-1)) by CV method. Long-term stability of the capacitor has also been tested by CV method, and the results indicated that, after 500 cycles, the specific capacitance of PANI/CuO nanocomposite film is 81.82 % of the initial capacitance. An equivalent circuit model of R (s)(C (dl)(R (1)(Q(R (2) W)))) has been used to fit the experimental and theoretical data.