Polyaniline (PANI) was synthesized chemically in an acidic medium in the presence of ammonium persulfate (APS) as an oxidizing agent. PANI/montmorillonite nano-composites were prepared in the presence of various amounts of modified clay (from 1 to 5 wt.%) by solution casting method. The free standing film of polyaniline and PANI/clay nano-composites was obtained by vaporization of solvent contain. Products were characterized by FT-IR spectra, SEM image, and XRD pattern. Thermal stability was also studied by TGA analysis, electrical conductivity was measured by four point probe technique and mechanical properties were studied by tensile strength. The PANI/clay nano-composites thermal and mechanical properties were observed to be remarkably improved. For example, polyaniline containing nano-clay has less weight loss compared to pure polyaniline. In addition Young’s modulus and strength at break point was increased in the case of polyaniline containing nano-clay The importance of our work is to provide a narrow look on the thermal and physical properties of polyaniline by the incorporation of montmorillonite into its structure as well as investigation of the conductivity of PANI/MMT nanocomposites as a potential conductive polymer to be used in solar cells or have corrosion protection applications.