Electrochemical copolymerization of N-methylpyrrole (NMPy) and indole (In) in various monomer ratios were carried out by potentiodynamically methods in acetonitrile electrolyte containing LiClO4 on gold electrode. The obtained homopolymers and copolymers were characterized with cyclic voltammetry (CV), in situ UV-Visible, FT-IR spectroscopy, scanning electron microscopy (SEM) and in situ resistivity measurements. The cyclic voltammetry study shows that the onset potential for the monomers and co monomers curves is located at the different values for N-methylpyrrole, indole and N-methylpyrrole-indole. There is a nucleation process followed by growth of nuclei to continuous films. The oxidation and reduction peaks for copolymer, P(NMPy-In), which synthesized from the 1: 1 mole-mole ratio concentration of the relevant monomers, located between those for poly N-methylpyrrole (PNMPy) and polyindole (PIn) films. The observed values were showed a decreased [NMPy]/[In] ratio concentration in the copolymers shifts the peak potential to more positive. The in situ UV-Visible, FT-IR spectroscopy and SEM analysis of homopolymers and copolymers were also studied. The result shows the intermediate spectroscopic properties between homopolymers and copolymers. The in situ resistivity measurements showed that the copolymers have a lower conductivity than the corresponding parent homopolymers. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.023204jes] All rights reserved.