In this paper, we demonstrate the electrochemical synthesis of a copolymer of N-phenylsulfonyl pyrrole (PSP) with 3,4-ethylenedioxythiophene (EDOT) as thin films on single carbon fiber microelectrodes. The deposition conditions on carbon fiber and the influence of monomer concentrations on the copolymerization were shown, as well as the electrochemistry of the resulting copolymers. The inclusion of PSP in the copolymer structure was also confirmed by Fourier transform IR-attenuated total reflectance spectroscopy, where the highest low frequency capacitance (C(LF)) was obtained for the mole fraction of PSP 0.86. Poly (EDOT-co-PSP) exhibits high capacitances compared to that of poly(3,4-ethylenedioxythiophene), which was shown by electrical impedance spectroscopy and equivalent circuit modeling (ECM). n values obtained from the ECM indicates the porosity of the electrode, which almost remains constant as similar to 1 for X(PSP) = 0.00,0.66,0.86. Charge-transfer resistance (R(1)) shows an increasing trend with PSP inclusion into the copolymer due to the partial destruction of conjugation. The double layer capacitance (C(dl)) has also shown a similar behavior. Both of these parameters have exhibited an almost linear relationship with the thickness of the film. The film resistance (R(2)) was between 0.88 and 10 k Omega cm(2). According to the calculations from the ECM, the inclusion of PSP in copolymer improved the capacitance and diffusion properties. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3490420] All rights reserved.