In this study, aniline (ANI) was electropolymerized on three different electrodes; platinum (Pt), glassy carbon (GC), and carbon fiber micro electrodes (CFME) in acid aqueous solution (0.5 M H2SO4) by cyclic voltammetry (CV). Electrode / PANI / electrolyte system was studied by electrochemical impedance spectroscopy (EIS). The results indicate the choice of electrode has a little effect on anodic (E-a) and cathodic peak potentials (E-c) during electropolymerization process. An equivalent electrical circuit ( R( Q( R( C( R( C( RW))))( CR)) was proposed for PANI on three different electrodes. The highest low frequency capacitance (C-sp= 120 mF /cm(2)) was obtained for PANI/Pt electrode compared to PANI/CFME (239.1 mu F /cm(2)) and PANI / GC ( 38.9 mu F /cm(2)) electrode. However, the highest double layer capacitance was obtained for PANI / CFME (C-dl = 190.9 mF /cm(2)) than Pt electrode (58.2 mF /cm(2)) and GC (24.3 mF /cm(2)).