Polytetrafluoroethylene (PTFE) was subjected to 1 MeV electron beam irradiation in air. The thermal stability and the degradation fragments of the irradiated polymer were studied in dependence on the radiation dose up to 4 MGy by thermogravimetric analysis coupled with mass spectrometry. The TGA results confirm the known decrease in the thermal stability of irradiated PTFE with increasing radiation dose. At the thermal degradation, CO2, HF, and fluorocarbon fragments are evolved from the irradiated samples. CO2 and HF are formed by decomposition of peroxy radicals up to 250 degrees C. In addition, low molecular weight fluorocarbons are desorbed from the irradiated PTFE. At temperatures above 300 degrees C, CO2 is formed by the decarboxylation of radiation-induced COOH groups inside the PTFE.