A series of electrically conductive poly(3,4-ethylenedioxythiophene) (PEDOT)/clay nanocomposites were synthesized by using oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of unmodified and modified montmorillonite. Modified montmorillonite was treated by dimethyl benzyl octadecyl ammonium chloride. Sodium dodecylbenzene sulfonate (DBSNa) was used as a surfactant in the polymerization of EDOT. PEDOT/montmorillonite (MMT) and PEDOT/organophilic montmorillonite (OMMT) nanocomposites were characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) means of investigation. Conductivity measurements of the synthesized samples were also taken. Electrical conductivity of the nanocomposites was found to be dependent on the clay content and the methods of preparation. The highest conductivity value, as high as 0.017 Scm(-1), was achieved for PEDOT/montmorillonite (MMT). The measurements on thermal properties showed a lower thermal decomposition rate for the PEDOT/MMT nanocomposites with respect to the PEDOT.