Conductive polymers are highly nanostructured materials formed by organic building blocks. The presence of delocalized molecular orbitals in these polymers makes them conductive. Present work deals with the study of polyaniline based conductive polymers synthesized by bulk oxidative chemical polymerization using ammonium per sulfate as an oxidant. The conductive polymeric materials were investigated by thermo gravimetric analysis (TGA), UV-visible studies confirmed the structure of synthesized polymers. TGA studies shows that polymeric materials are thermally stable upto about 150oC, above this temperature degradation of polymeric material starts. Slight structural and morphological changes are observed in TEM images with change in substituent in monomer units.