The PT/PS/SiO2 nanocomposite of polythiophene (PT), polystyrene (PS), and SiO2 with a grain size of 100-150 nm was synthesized by chemical polymerization using FeCl3 oxidant in nanoqueous medium (CHCl3). The properties of PT/PS/SiO2 synthesized were compared to those of PT, PT/PS, and PT/SiO2 synthesized in the same conditions. The synthesized materials were subsequently characterized by FTIR spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The incorporation of PT in the composite was endorsed by FTIR studies. TGA revealed enhanced thermal stability of the PT/PS/SiO2 nanocomposite compared to that of PT. SEMs showed globular particles and the presence of clusters of composite particles. The conductivity of the PT/PS/SiO2 nanocomposite was measured as 1.30 X 10(-7) Scm(-1) and the conductivity value of PT (1.02 X 10(-4) Scm(-1)) decreased with entiring PS and SiO2 to PT structure. (c) 2005 Wiley Periodicals, Inc.