In this communication, a series of thiophene-indole conducting copolymers are successfully synthesized via in situ chemical oxidative copolymerization of thiophene and indole monomers using anhydrous FeCl(3)as an oxidant. Fourier-transform infrared spectroscopy studies depict the structural confirmation. X-ray diffraction profile indicates the amorphous nature of the as-synthesized copolymeric samples. The electrical conductivity, dielectric properties and relaxation model are indeed studied using AC impedance spectroscopy technique in the frequency and temperature ranges 20 Hz-1 MHz and 303-393 K, respectively. The temperature dependence of electrical conductivity of as-prepared copolymeric samples followed the Arrhenius relation. The variation of AC conductivity with frequency obeys the Jonscher's power law. The electric modulus spectra showed the non-Debye nature of the studied copolymeric materials. Graphic abstract Schematic for in situ synthesis of thiophene-indole conducting copolymer through chemical oxidative copolymerization route