A solution-solid equilibrium in ternary water-organic systems CuCl ₂-L-H₂O (L = dimethyl sulfoxide, N,N-dimethyl formamide, and acetonitrile) at 25°C was studied. The expansion of crystallization branches of individual solvates CuCl₂•xL varies in parallel to the donor power of organic solvents. The existence of the mixed crystal-solvates CuCl₂•2H₂O•2(CH₃)₂SO, CuCl₂•2H₂O•2(CH₃)₂NCHO, CuCl₂•H₂O•(CH₃)₂NCHO, CuCl₂•2H₂O•CH₃CN, and CuCl ₂•3H₂O•2CH₃CN in the studied systems was proved. Various donor power of oxygen-containing solvents determines the composition of the first coordination sphere of the copper ion in the specified compounds: the coordination of the both solvents in the mixed crystal-solvates with DMF and the absence of water in the nearest environment of the copper(II) ions in the CuCl₂•2H₂O•2(CH₃) ₂SO compound.