In this study, the degradation performance of 2,4-Di-tert-butylphenol (2,4-D) by the ultraviolet/persulfate (UV/PS) process was evaluated for the first time. To better understand the possible degradation mechanism in the UV/PS advance oxidation process system, a kinetic model involved hydroxyl and sulfate radicals was developed for predicting pseudo-first order rate constants (k(o)) and radical contributions. The results showed that the degradation of 2,4-D was promoted by increasing dosages of PS. H2PO4- almost had no significant impact on the degradation of 2,4-D, whereas the removal of 2,4-D was suppressed when NO3- dosage was added up to 50 mM. HCO3-, HPO4- and natural organic matter significantly inhibited the degradation of 2,4-D. The reaction rate constants between SO4 center dot- and 2,4-D were not affected by pH. However, the degradation was suppressed with the increasing pH due to the increasing HPO42- from the phosphate buffer in alkaline. The degradation of 2,4-D was promoted by adding Cl-. The proposed degradation pathways were elucidated on the basis of results obtained by high-performance liquid chromatography combined with triple quadrupole mass spectroscopy analysis. (C) 2016 Elsevier B.V. All rights reserved.