Experimental results on the ΔHsoln of noble gases, polar non-electrolyte molecules, porphyrins, their metallocomplexes and organic electrolytes in individual and mixed solvents are discussed. Xe was shown to indicate changes in solvent mixtures and also to exert a noticeable influence on the character of intermolecular interactions in solutions. The thermodynamic characteristics of the solvation of a series of non-polar and polar molecules are given and their dependence on the solvent nature, composition, isotopy and temperature is shown. For the first time the thermodynamic characteristics of porphyrins and metalloporphyrins in different non-aqueous solvents have been found by direct calorimetry. The possibility of axial coordination of porphyrin metallocomplexes is treated and a method is proposed for estimation of the influence of the functional substituents and the metal atom on the electronic effects in them. Compared to simple inorganic electrolyte solutions, the dependence of ΔHsoln on various factors reveals a specific character.