Experimental data on solvent extraction of lanthanum (III) and samarium (III) by solutions of naphthenic acid from nitrate medium was obtained. Dependences of distribution coefficient of pH, concentration of organic and aqueous phase was obtained. thermodynamic characteristics of extraction equilibrium was calculated.

Technology of solvent extraction and separation of cerium lanthanides by solutions of naphthenic acid in o-dimethylbenzene was obtained. The sequence of extraction Eu > Sm > Ce > La from nitrate media was calculated.

Experimental data on solvent extraction of lanthanum (III) by solutions of oleic acid from nitrate medium was obtained: process direction, dependences of distribution coefficient of pH, concentration of organic and aqueous phase, thermodynamically characteristics of extraction equilibrium.

Experimental data on solvent extraction of cerium (III), yttrium (III), lanthanum (III) by solutions of oleinic acid in o-dimethylbenzene was obtained. The possibility of extraction sepa- ration of cerium(III), yttrium(III), lanthanum (III) from nitrate media was shown.