The physical and technical aspects of the transition to a new definition of the unit of temperature as a physical quantity are considered, and the features of the implementation of the absolute method of its reproduction in radiometric thermometry are revealed, the physical foundations of the method and its theoretical justification are presented. A comprehensive analysis of the procedure for reproducing the temperature unit according to its new definition is given, features of the implementation of the method in reference radiometric thermometry are shown, and an estimate of the measurement error is given.