A novel poly 3-(2-benzo thiazolyl) thiophene based conductive polymer have been synthesized and characterized using various experimental techniques. The structure and band gap (difference between Highest Occupied Molecular Orbital and Lowest Unoccupied Molecular Orbital) for the above polymer have been calculated using oligomeric approach employing B3LYP/3-21G* method and semi-empirical AM1 and ZINDO methods. The calculated band gap for monomer, dimmer and trimmer has been plotted versus 1/N (where N is the number units). The value at 1/N=0, is taken as the band gap of the polymer having long chain length. It is evident from the theoretical investigations, the band gap of poly 3-(2-benzothiazolyl) thiophene is 3.77 eV. It is possible to change the band gap by designed alteration in the thiophene framework.