The partition coefficients for five phenolic compounds in the ionic liquid + water two-phase system were measured at 298.2 K by a static method. The ionic liquid focused on in this work was 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]). The effects of isomers for phenolic compounds on the partition coefficients were investigated. The partition coefficients of 2-ethylphenol are larger than those of 3- and 4-ethylphenols. For the phenols with three methyl or methylene groups, the partition coefficients or 2,3,5-trimethylphenol are higher than those of 4-propylphenol. An activity coefficient equation based on a conductor-like screening model was used for the prediction of the partition coefficients. The predicted results are in agreement with the experimental data within the order of magnitude of the partition coefficients. The profiles of the surface charge densities of the phenolic compounds on CH and OH groups for the phenols were used for the investigations of the isomer effects on the partition coefficients.