The less-volatile compounds forming a smoke emitted during the thermal degradation of poly(ethylene terephthalate) (PET) in different conditions were studied. Thermal degradation of PET was carried out within the temperature range of 200 -700 degreesC in both a nitrogen and an air atmosphere. The less-volatile thermal degradation products were trapped on a glass-fiber filter and analyzed by capillary gas chromatography with mass selective detector (GC-MS) and high performance liquid chromatography (HPLC). The results are collected in tables and presented on plots as a function of the degradation temperature. The temperature and atmosphere effects on the emission and composition of the smoke during PET thermal degradation were considered.