Introduction. Polymeric thermal-insulation materials (EPS, XPS, polyurethane foam etc.) is widely used in buildings, including high-rise buildings. The fires in such buildings may lead to the mass death of peoples. Purpose and objectives. The aim of this work is studying the thermal behavior of the thermal insulation from expandable polystyrene (EPS 10, EPS 14) and the new foamed composite “Penocom”. For this purpose, effective kinetic parameters (activation energy, pre-exponential factor) of thermal and thermo-oxidative degradation of the chosen polymeric materials were determined. Also, physical mechanisms of degradation in the air and inert environment were determined. Also, linear thermal shrinkage for a broader list of organic and mineral thermal insulation materials was determined. Methods. Processes of thermal degradation were investigated with thermogravimetric analyzer Mettler Toledo TGA/DSC. Linear thermal shrinkage was determined with muffle furnace at heating rate 12 °C/min. Results. Degradation of the EPS in the air and inert environment occurs in the liquid state. Reaction order n = 1, nucleation mechanism R (1). The complex nature of thermal decomposition and pyrolysis is observed when heating foamed composite “Penocom” with a bulk density r = 140 kg/m3. In the air environment, the degradation process is carried out by diffusion mechanism D3, in the inert environment - by nucleation mechanism R (1). The linear thermal shrinkage of EPS 14 was 100 % at 170 °C, Penocom - 60 % at 650 °C. Conclusions. Analysis of experimental results has allowed determining thermal behavior of chosen polymeric thermal insulation materials. This results can be used, for instance, in fire modeling.