The Doctoral Thesis is devoted to the research of wood plastic composites (WPCs) made with thermally modified wood residues. Their suitability for the production of WPC has been analysed, as well as the main influencing factors. Physical, mechanical, and service properties of the obtained WPC have been studied, identifying the advantages, disadvantages, as well as the tendencies of the changes in the properties depending on various factors. Knowing that moisture resistance is one of the main shortcomings of WPC, special focus was attributed to investigation of these aspects. Different mechanisms responsible for the characteristics of these materials are also explained.