The full scale experimental assembly for study of the hydrogen isotope separation by cryogenic distillation is described. The cryogenic column has the diameter up to 300 mm, height of 5,5 m and place in the vacuum jacket diameter of 1200 mm and height of 6,5 m. There is a possibility to change the mass exchange sections of the column with various packings replacing of sections with diameter from 80 to 300 mm. Circulation gas flow in the column is up to 10 kMol per hour. Hydraulic and separation characteristics of the mass exchange packings of various types were studied by using the next working mixtures: Ar-O2, o-p-H2, H2-HD-D2, HD-D2-DT. The best values of the height transfer unit (HTU) were obtained for the packing produced from copper wire and put through chemical treatment and plate type with a small distance between plates. HTU was equal respectively 5–6 cm and 7–8 cm. A set of experiments was carried out for the improvement and understanding of the problems connected with safety of detritiation plant, for example, the freezing of air on the cryogenic surfaces of the column when in the jacket the microcrack is formed during operation and et. al.