Based on the systematic analysis of experimental data for liquid-liquid extraction of the substituted phenols, the F a and F mu parameters have been suggested to describe the dependence of log P 0 (P 0 is the distribution coefficient) from the energy of universal intermolecular interactions in solutions and the structural characteristics of solutions in non-polar and polar solvents correspondingly. The deviations from the dependences of log P0 = f(F a) and log P0 = f(F mu) show the contribution of specific interactions (H-bonds) to the process of extraction. The method is aimed at determination of the ionization constant of phenol (K a ) on the basis of phenol distribution between the water and non-water solvents, which do not mix up with water. It is shown that the ?K a values of the substituted phenols obtained by the measurements in water and non-water solvents depend on s0-constant. The influence of the amount of the same substituents in the phenol molecules on the ?K a values was studied.