The partition coefficients and solubilities in octanol, water and mutually saturated octanol - water phases were determined for sorne sulfonamides at 25.0 ± O.I°C. Using the solubility data, enthalpies of fusion and melting temperatures, the activity coefficients of the solutes in the aqueous and organic phases were calculated. From these results the intermolecular interactions among the solute and solvent molecules were estimated. As in other studies made with guanine derivatives, it has been shown that the mutual saturation of the octanol and aqueous phases plays an important role in the partitioning of the evaluated sulfonamides.