The present monograph is intended to provide a systematic review of the properties and mathematical modelling of concrete at high temperatures. It is intended for university researchers and graduate students in civil engineering and materials science, as well as practicing engineers occupied with fire resistance, chemical technology vessels or nuclear reactor structures. Part 1 of the book, written mostly by the second author, deals with material properties and behaviour, in a descriptive nonmathematical manner. It calls for a background at the B.S. level in civil engineering or material science, including the basic courses in mechanics, in concrete technology and design, and in material properties. Some portions of Part 2, devoted to mathematical modeling, can be understood on the basis of the same background; however, much of Part 2, written by the first author, requires a deep erudition in mathematics, mechanics and physics, at least at the M.S. level. Although the book is not a textbook, it can be used as reference for courses on the properties and mechanic of concrete.