Degradation of diisobutyl phthalate (DIBP) by Fenton oxidation was evaluated in this study. The results indicate that the pH, H2O2 and Fe2 + concentration were three main operating factors considerably affecting the decomposition of DIBP. The optimum conditions were observed at pH 3 and the molar ratio of [H2O2]: [Fe2 +]: [DIBP] = 5: 5: 1. Under such condition, the maximum removal of DIBP was as high as 87% at a time of 30 minutes. In general, the empirical equation was derived as follows: (dCDIBP/dt)initial = -k CDIBP,00.88CFe2 +,00.33CH2O20.95.