The increased occurrence of thermo-treated wood "ThermoWood" in the wood processing industry raises the need to assess the impact of thermal modification of wood on its fire risk. Diploma thesis deals with the assessment of the impact of thermal modifications of wood forest pine (Pinus sylvestris, L.). The samples were thermally treated at temperatures of 160 °C and 200 °C for 3 and 9 hours, and one group of pine wood samples remained untreated. The samples were tested on the basis of the ignition temperature and flash point test in accordance with the standard STN ISO 871 (2010). Thermal treatment of the samples at the indicated temperatures had no significant effect on the flash point and ignition temperatures. The biggest effect has thermal treat at 200 °C for 9 hours, where the flash point was 350 °C, the other samples reached a flash point of 340 °C. The ignition temperature of all samples was 420 °C.