Partition properties have been determined for 28 monosubstituted phenols in the sodium dodecylsulfate (SDS)/water system by micellar liquid chromatography (MLC), offering a useful and versatile method to estimate the hydrophobicity of compounds. The enthalpy and entropy terms of partition have also been determined from variable temperature experiments on MLC and are interpreted by such factors as molecular size and hydrogen-bond ability of the solute. The pi constants (pi, pi H and pi S) are determined from the experimental partition properties and applied to quantitative structure-activity relationships (QSAR) analysis, and their versatility supported.