The textbook includes the basic concepts and laws of technical thermodynamics, applications of these laws to thermodynamic processes and systems. Materials of two main methods of engineering calculations - analytical and thermodynamic diagrams method are well presented. The thermodynamic foundations of chemical reactions with the introduction of "free" energy and enthalpy are considered, which lays the foundations of many technical processes in industrial heat engineering: in fuel cells, in electrochemical generators, in various kinds of energy transformations that are not related to the work of changing the volume of the working fluid. The textbook is written at a high scientific and methodological level, accessible and simple, intended for thermal power students.