Quantum mechanical calculations are performed to establish the structure of an oligomer of aniline and pyrrole [Poly(Ani-co-Py)], through comparison of experimental and theoretically calculated properties, including conductivity. The copolymer was synthesized through chemical oxidative polymerization and then confirmed from the experimental IR, UV-vis, mass spectra, elemental, XRD, TGA, and SEM analysis. Quantum mechanical calculations are performed at Density Functional Theory (DFT) and Time dependent DFT (TD-DFT) methods for the electronic and spectroscopic properties of the oligomer. A very nice correlation is found between the theory and experiment which consequences the structure of Poly(Ani-co-Py). Poly(Ani-co-Py) is not explored like other conducting polymers; however, by tuning this molecular structure, the electro-active nature of this material can be enhanced adequately. (C) 2015 Elsevier Ltd. All rights reserved.