The textbook "Thermomechanics of Composites under High Temperatures" by Yuriy I. Dimitrienko provides a comprehensive analysis of the thermomechanical properties of polymer-based composites at high temperatures. It explains how the mechanical and thermal properties of these materials differ at elevated temperatures compared to normal temperatures. In particular, it addresses the irreversible changes that occur at high temperatures, as well as the complex physico-chemical processes taking place in the matrix and fibers. These processes lead to significant internal thermal stresses and render the composite a multiphase system consisting of solid, gaseous, and liquid phases that interact mechanically and chemically. The book is a valuable resource for professionals and students dealing with the challenges and properties of composites at high temperatures.