The stabilities of the complexes of metal ions with macrocyclic ligands in solutions are largely dependent on the solvation of each species involved in the complexation  equilibria. The transfer activity coefficients of the solutes are important values expressing the relative strength of solvation in different solvents quantitatively. In this review, the transfer activity coefficients of metal ions (alkali metal ions, Ag⁺, T1⁺, Ba²⁺) and neutral macrocyclic ligands (crown ethers, cryptands) between nonaqueous solvents (acetonitrile, propylene carbonate, methanol, dimethyl- formamide, and dimethyl sulfoxide) and water and the stability constants of their complexes in the solvents are collected from the literatures and overviewed; Using these data, the transfer activity coefficients of the complexes are calculated. The specificity of water in solvation for the ligands and their metal complexes and its contributions to the complex formation are thoroughly discussed.