The separation of Sc and Y from the lanthanides by extraction with various quaternary ammonium salts was investigated. Aliquat-336,methyltrioctylammonium nitrate (MTOA), methyldibutylhexadecylammonium nitrate (MDBHDA) and tributylhexadecylammonium nitrate (TBHDA) were used as extractants. The synthesis of MDBHDA and TBHDA from industrial products is described. From the results obtained in the extraction studies of REE as a function of the parameters of aqueous and organic phases, we have determined the optimal separation conditions. The salting-out action in these systems of a great number of cations such as Al3+, Fe3+, Mg3+, Cu3+, Ni3+, Li3+, Cs3+, was investigated. To determine the functional dependences of the separation factors for the REE, the viscosity of the water layer around the ion was used.