Adsorbtion isotherms, from water solution onto activated carbon have been determined over a wide consantration range for phenol and some its derivatives. At the first look, it was observed that the experimental data of 3-hydroxyphenol (resorsine) agree with predicted isotherm calculated by the Hansen-Facker modification of Polanyi Adsorption Potential Theory, using only the solute refractive index and molar volume, together with characteristic curve for the carbon as determined from gas-phase adsorption data but, 4-nitrophenol isotherm agree with the theoretical isotherm after correction for its hydration and corrected experimental curves of phenol, 2, 4-dinitrophenol and 2,4,6-trinitrophenol appear to be related to the theoretical isotherm by single abscissa scale factor.