The concept and classification of thermal turbines. Historical development. Fields of knowledge application in thermal turbines. Thermodynamic and Electrical foundations. Characteristics of compressible fluid flow. Expansion and compression without friction in the nozzles. Expansion and compression with friction in the nozzles. Efficiency of expansion and compression in turbines (polytropic, isentropic, isothermal degrees of utilization). Working on scope (classical and aerodynamic method, force, momentum and power on scope, for blades without and with cooling). Utilization degree on the scope of axial degrees: action and reaction – Parson`s, individual and from the group. Comparison of action and Parson`s degrees. Curtis degree. Comparison of degrees with multiple degrees of speed. Axial turbine degree with cooling petals. Utilization degree on the scope of degrees of radial turbines (centrifugal – Ljungstrem and centripetal). Utilization degree on the scope of compressor degrees (for three definitions from the engineering practice). The meaning of degrees of thermal turbines. Losses in the degree (because of vapor humidity, on friction and ventilation, because of partial filling and through fissures). Turbulent flow in the degrees of thermal turbines – simple equation of radial balance. Energy transformation in the cycles of thermal turbines (Joule`s – without cooling and with cooling, Rankin`s and combined Joule –Rankin`s).