The mechanisms of the process of extractive regeneration of oligomerization catalysts based on pillared clays in supercritical carbon dioxide (SCF-CO (3) ) in pure state and with addition of chlorine compounds (CCl (4) or C (2) H (4) Cl (2) ) are studied. The catalyst efficiency in the oligomerization process after regeneration with various SCF solvents is compared. The carburized and regenerated catalysts are studied by thermal analysis methods. Chlorine-containing additives are found to be effective in the regeneration process.