This thesis reports the knowledge about thermal modification of wood by domestic and foreign authors with respect to the advantages and purpose of use of this material. The objective of this study was to evaluate an effect of thermal treatment on selected properties of wood. The study presents the experimental part, which included the development of a test methodology for determination of selected properties of the thermally modified wood as well as the preparation of the material and the implementation of the experiment with the subsequent evaluation of the results. The research was performed on wood beech (Fagus sylvatica L.), which we thermally modified in the oxidizing atmosphere at the temperatures of 160, 180 and 200 ℃ for 1.5 and 3 hours. Then we determined the equilibrium moisture content, the dynamic modulus of elasticity and, from the mechanical test, the strength of the wood parallel to the grain, the modulus of elasticity and the Poisson's ratio on the individual samples of test specimens. The results showed a decrease in hygroscopicity, a slight increase in compressive strength parallel to the grain, a decrease in the modulus of elasticity and a decrease in Poisson's ratio, which suggested an increase in the brittleness of wood due to thermal treatment.