n-Butyl benzyl phthalate (BBP) has been classified as endocrine disrupting compound and priority pollutant. Effects of TiO(2) dosage, pH, initial BBP concentration and co-existing substances on the degradation of BBP by TiO(2)/UV process were investigated. The optimal TiO(2) dosage and pH value for the BBP degradation were 2.0gL(-1) and 7.0, respectively. The degradation rate of BBP by TiO(2)/UV process could be fitted pseudo-first-order kinetics. The effects of co-existing substances on the degradation rate of BBP revealed that some anions (such as BrO(3)(-), ClO(4)(-) and Cr(2)O(7)(2-)) could enhance BBP degradation, and other anions would restrain BBP degradation. The sequence of inhibition was PO(4)(3-)>CO(3)(2-)>NO(3)(-)>SO(4)(2-)>Cl(-). The cations K(+), Na(+), Mg(2+) and Ca(2+) had the restrained effect on the BBP degradation, and the effect of Ca(2+) was the strongest among four cations tested. The organic compounds acetone and methanol decreased the degradation rate of BBP. The major intermediates of BBP degradation were identified as mono-butyl phthalate, mono-benzyl phthalate and phthalic acid, and a primary degradation mechanism was proposed.