Solvation of europium ions in mixed aqueous-organic solvents was studied in the solutions of europium(III) triflate and chloride. Europium ions are preferentially solvated by organic solvent only in waterdimethylsulfoxide systems. In aqueous dimethylformamide and dimethylacetamide preferential hydration in water-deficient region was observed. The total solvation number was proved to decrease from 9 in neat water to 8 in neat dimethylsulfoxide and dimethylformamide and to 7 in neat dimethylacetamide. The formation of chlorocomplexes in neat water and aqueous dimethylacetamide was observed. (C) 2017 Elsevier B.V. All rights reserved.