[en] The fundamental radiochemical properties of technetium are reviewed as is its role in spent fuel reprocessing. The basic properties are also shown of technetium hexafluoride resulting from oxide fuel fluorination. Sorption-desorption and distillation techniques are described for the separation of TcF₆ and other fluorides and oxyfluorides of fission products from UF₆ and PuF₆. Industrial equipment is also described for fast reactor spent fuel reprocessing where technetium is separated by the fluoride method. The equipment handles 1 ton of spent fuel a day with a resulting decontamination factor of 10⁶ to 10⁷. The composition is shown of fission product contaminants forming volatile fluorides. Technetium hexafluoride may also be separated from UF₆ by means of contact with a nickel mesh at 400 to 500 degC. In the fluoride separation of technetium from UF₆, sorption on NaF and MgF₂ adsorbents was used. The establishment of the most suitable selective sorption conditions and the achievement of reproducible behaviour of TcF₆ in the MgF₂ sorption bed will allow technetium separation and its application in other fields. (J.P.)