The partition of various chlorinated and nitrated phenols between hydrophobic ionic liquids and aqueous solutions of different pH values was investigated at 298.2 K. Ionic liquids used are 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([BMIm] [NTf(2)]), 1-butyl-1-methylpyrrolidinium bis (trifluoromethanesulfonyl)amide ([BMPyr] [NTf(2)]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF(6)]), 1-methyl-3-octylimidazolium bis(trifluoromethanesulfonyl)amide ([OMIm][NTf(2)]), and 1-methyl-3-octylimidazolium tetrafluoroborate ([OMIm][BF(4)]). Partition coefficients (P(IL/W)) of the electrically neutral form (ArOH) and the dissociated anionic form (ArO(-)) were determined. For a given phenol, the P(IL/W)(ArOH) value in the ionic liquid/water system is generally independent of the kind of the ionic liquid and smaller than that in the 1-octanol/water system. Exceptionally, the P(IL/W)(ArOH) value in the [OMIm][BF(4)]/water system is larger than those in the other ionic liquid/water systems and comparable to or greater than that in the 1-octanol/water system. The interaction energies of the ionic liquids with the phenolic hydroxyl group were evaluated. It is shown from the dependence of the interaction energy on the acid-dissociation constant of the phenol that the ionic liquid behaves as both an electron-pair donor and an acceptor like water rather than 1-octanol. The P(IL/W)(ArO(-)) value depends largely on the kind of ionic liquid, showing that an ionic liquid formed by a more hydrophobic cation and a more hydrophilic anion has a higher extractability for the phenolate anions. The substituent effects on P(IL/W)(ArO(-)) are also different from those on P(IL/W)(ArOH).