FIELD : pharmaceuticals.SUBSTANCE : invention relates to a method of producing 2-perfluoromethylpentene-2 by dimerisation of hexafluoropropene, which is fed 0.15–0.5 l/min at temperature of 200–350?°C per catalyst. Dimerisation is carried out at excess pressure of 100–700 kPa, and said catalyst is active carbon with applied CsF, which is pre-dried in a reactor at temperature of 105–120?°C under vacuum, and then at temperature 250–350?°C, with alternation of nitrogen blowing and evacuation, absolute pressure in both cases is 66.5–1.33 kPa.EFFECT : obtaining 2-perfluoromethylpentene-2 with output of more than 95?% and selectivity of more than 97?%, simple process technology.1 cl, 4 tbl, 46 ex