The paper is concerned with the solvation of Li+, Be2+, Na+, Mg2+, and Al3+ ions in the mixed solvents acetonitrile···water, dimethyl sulphoxide···water, and dimethylformamide···water. The complexes acetonitrile···ion···acetonitrile are also studied. The ab initio quantum chemical method with the minimal STO-3G basis set was used to calculate the equilibrium distances, solvation energies, three-particle energy contributions, charge distributions, and overlap populations for the above systems. Optimum structures of the 1 : 1 : 1 complexes were determined on the basis of the results obtained.