Allyl methacrylate, AMA was polymerized in CCl4 solution by alpha,alpha'-azoisobutyronitrile at 50 degrees C. The thermal degradation mechanism of PAMA was characterized by MS, TGA-FT-IR and FT-IR-ATR methods. The mass spectrum and TGA thermogram showed two stage degradation. The first stage of degradation was mostly linkage type degradation for the fragmentation of pendant allyl groups at 225 - 350 degrees C. In the second stage, at 395 - 515 degrees C, the degradation is random scission and depolymerization types. This was also supported by direct thermal pyrolysis of polymer under vacuum. The degradation fragments of MS and TGA were in agreement. In the degradation process, monomer degraded further to CO, CO2, allyl and ether groups. No strong monomer peak was observed in mass spectrum.