Abstract-The T 100 12.8 turbine and its versions, a type of cogeneration steam turbines that is among best known, unique, and most widely used ones in Russia and abroad, are considered. A list of turbine design ver sions and quantities in which they were produced, their technical and economic indicators, design features, schematic solutions used in different design versions, and a list of solutions available in a comprehensive port folio offered for modernizing type T 100 12.8 turbines are presented. Information about amounts in which turbines of the last version are supplied currently and supposed to be supplied soon is given.