The presented article is focused on the impact of thermal modification on the selected properties of beech wood (Fagus sylvatica L.). Our observations is based on the changes properties like a density, swelling and EMC. The test specimen, which put to the tests thermal treatment in oxygen atmosphere with used unchanged pressure. Thermal treatment were realized with temperatures 160, 180, 200 °C during 1,5 – 3 hours. Determination of properties before and after thermal treatment. Our findings put forward that density is changed minimal during thermal treatment, but swelling and EMC are decrease. This is confirmed by ASE coefficient. The findings reveal the advantages of thermal modification in view of the targeted change in the physical properties of wood.