The thermal behavior of poly(methyl methacrylate) (PMMA) was studied in the presence of AlBr₃ using TG-DTA-DTG, IR and Py-GC-MS techniques. Degradation products were identified. It was found that PMMA started degrading at a lower temperature due to the generation of free radicals (Br^•), being the product of decomposition of AlBr₃. Despite early destabilization of the system, stabilization zone was also highlighted. Flammability test was conducted to check the affectivity of AlBr₃. Degradation mechanism has been proposed. Pyrolysis of the system (PMMA–AlBr₃) was also monitored by heating it at different temperatures.