In this work, we presented a novel conducting poly (p-nitroaniline-co-N-methylaniline) (P(p-NAn-co- NMAn)) material, obtained by electrocopolymerization of para-nitro aniline (p-NAn) and N-methyl aniline (NMAn) in aqueous sulfuric acid solution. The purposes of this research are investigation and characterization properties of synthesized copolymers and investigation of catalytic effect of NMAn on the polymerization of para-nitro aniline. Electrosynthesis was carried out using cyclic voltammetry technique with different monomer feed concentrations. Characterization of samples were carried out by cyclic voltammetry, in situ conductivity measurements, scanning electron microscopy (SEM), in situ UV– vis, and FT-IR spectroscopy techniques. The cyclic voltammograms of P(p-NAn), P(NMAn) and P(p-NAn- co-NMAn) showed that the peak potentials were located at different values due to different monomer concentration employed during the electrosynthesis process. The in situ conductivity of the p-NAn-co- NMAn increased with increasing the [p-NAn]/[NMAn] concentration ratios. Mechanisms of polymerization and copolymerization reactions of homo and copolymers were suggested. The in situ UV–vis. spectroscopy results revealed strong absorption bands at different applied potentials and a spectroscopic behavior of copolymers intermediate between that of the homopolymers. The FT-IR spectroscopy and SEM analysis results showed the fundamental differences between the structures and morphology of the homo- and copolymers.