Reported here in, is the synthesis of polystyrene (PS)-supported ZieglerNatta catalyst (PS-TiCl4) by the reaction of PS and titanium tetrachloride (TiCl4). PS was synthesized by emulsion polymerization using super critical CO2 (sc-CO2) as a medium. Three catalysts were synthesized by varying the TiCl4/PS weight ratio in hexane medium. The resulting catalysts were characterized by Fourier transformed-infrared spectroscopy, UVvisible spectroscopy, scanning electron microscope and energy dispersive X-ray detector, X-ray diffraction analysis. The acidity of the catalysts in an acetone/water solution was measured by pH meter. The thermogravimetric analysis reveals that catalysts are stable upto 150-180 degrees C. Due to their higher degree of thermal stability these catalysts may potentially be used as a support in conventional ZieglerNatta catalyst for ethylene polymerization. These catalysts also showed good storability and its overall catalytic productivity are found to be 3720 g PE/g Ti. The productivity of the catalysts also depended on the titanium concentration in the polymer matrix.(C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012