Experimental data on the solvate extraction of cerium(III) and yttrium(III) by solutions of oleic and naphthenic acids in o-dimethylbenzene have been obtained. After mathematical analysis of the dependences of the distribution coefficient on pH and the composition of the organic and aqueous phases, the structure and composition of the solvate complexes, as well as the values of Gibbs free energies and equilibrium constants of the reaction were determined.
