1-Octanol/water partition coefficients log K(ow) of 38 sulfonamides were determined by the isothermal saturation method. These values were used both for direct correlation and as test data for the verification of a regression equation for calculation of log K(ow) on the basis of two physicochemical descriptors (molecular polarizability, a surrogate for molecular size, and H-bond acceptor ability). Comparison of experimental and calculated K(ow) values demonstrated the wide applicability of those equations.