[en] Molybdenum (6) extraction with di-2-ethylhexyldithiophosphoric acid from solutions of mineral acids has been studied. It is shown that in the range of concentrations 0.01-1 N HClO₄ cation exchange extraction with the formation of molybdenyl di-2-ethylhexyldithiophosphate MoO₂ [(C₈H₁₇O)₂PSS]₂ takes place. Comparison of the molybdenum (6) extraction from perchlorid acid solutions with di-2-ethylhexyldithiophosphoric-And di-2-ethylhexylphosphoric acids has shown that, when sulfur is substituted for phosphoryl- and hydroxyl oxygen, the molybdenum distribution coefficients increase almost by an order. Concentration constants of equilibrium of molybdenum (6) extraction with di-2-ethylhexyldithiophosphoric acid for a number of diluents and with di-2-ethylhexylphosphoric acid for heptane are calculated