N-Isopropylacrylamide (NIPA) gel was prepared by free radical polymerization in the presence of tributyl phosphate (TBP) as the extractant species of phenols. Homogeneous hydrogel was found to form at 333 K in methanol and the concentration of crosslinker (NN'-methylenebisacrylamide) of 86 mM. The resulting NIPA gel incorporated with TBP was applied to the removal of phenol from aqueous solution. The removal efficiency of phenol using the hydrogel was greatly enhanced by the incorporation of TBP. The liquid-liquid solvent extraction of phenol using TBP was examined for the comparison of the distribution ratio D. From the proportional dependence of D on the amount of TBP, phenol was found to form 1:1 complexes with TBP both in NIPA gel and liquid-liquid solvent extraction. NIPA gel incorporated with TBP at a molar ratio [TBP]/[NIPA] = 1 exhibited considerably high removal efficiency (D = 74) compared to that obtained in the liquid-liquid solvent extraction.