Wood, as a material, offers several unique advantages: widespread availability, natural renewability, favorable ecological assessment, and flexibility of implementation. Moreover, the polymeric components of wood, together with its porous structure, confer upon it a faculty for transformation exceeding that of other materials.One of the emerging eco-friendly treatment methods is the combined use of temperature, moisture and mechanical action – the so-called thermo-hydro-mechanical (THM) and thermo-hydro (TH) treatments. THM processing is implemented to improve the intrinsic properties of wood, to produce new kinds of materials, and to acquire a form and functionality desired by engi- neers without changing the eco-friendly nature of the material. In this book, the authors bring together the key elements of the chemical degradation of wood constituents under TH and THM processing; a description of the behavior of wood under these conditions; as well as a selection of the principal technologies that can be considered TH/THM treatments.