In this study, the photocatalytic ozonation process using either UV lamps with a wavelength close to a solar wavelength (UV solar ) or natural solar light was established to study the effects of the major operating parameters on the removal of a toxic disinfection by-product (DBP), dichloroacetonitrile (DCAN), from drinking water. Based on the test results of a bench system, the UV solar /TiO 2 /O 3 process had the highest DCAN-removal rate among the advanced oxidation processes (AOPs). The optimal TiO 2 and ozone doses were 1gL −1 and 1.13gL −1 h −1 , respectively, while room temperature (20°C) produced the highest rate constant in the kinetic tests. The kinetic rate constants linearly increased when the UV solar intensity increased in the range 4.6–25Wm −2 ; however, it increased less at intensities higher than 25Wm −2 . The test results of the outdoor system showed that the solar/TiO 2 /O 3 process provided complete removal of DCAN that was two times faster and had about 4.6 times higher energy efficiency than with solar/TiO 2 . As a green oxidation technique, solar photocatalytic ozonation could be a good alternative for treating recalcitrant and toxic organic pollutants, because it has high oxidation potential and low energy consumption compared to conventional AOPs.