The preparation and polymerisation of 4-benzenesulfonylbenzyl methacrylate are described. Thermal degradation of poly(4-benzenesulfonylbenzyl methacrylate) [poly(BSBzMA)] was studied by thermogravimetry (TG), FT-IR and NMR. Programmed heating was carried out at 10 o C/min - 1 from room temperature to 500 o C. Residual products of poly(BSBzMA) at various temperatures were examined by FT-IR spectroscopy. The cold ring fraction (CRF) of products volatile at degradation temperature but not at ambient temperatures has been characterized by GC-MS, FT-IR, 1 3 C and 1 H NMR techniques. The main products in thermal degradation of poly(BSBzMA) are 4-benzenesulfonylbenzyl methacrylate and 4-benzenesulfonyl toluene. The other liquid products of the degradation formation of anhydride ring structures and mechanism of degradation are discussed.