Chlortetracycline (CTC) is a hazardous material in aquatic environment. This study was focused on optimization of photo-catalytic ozonation processes for removal of CTC from wastewater, at pH 2.2 and 7.0. In this study, the tested processes for CTC removal were arranged from the least efficient to the most efficient as: UV, UV/TiO2, O3, O3/UV, O3/UV/TiO2. Ozonation efficiency was due to ozone affinity for electron rich sites on the CTC molecule. In the O3/UV and O3/UV/TiO2 processes efficiency was increased by the photolysis of CTC and generation of ?OH. At pH 7.0, all the processes were more efficient for CTC degradation than at pH 2.2 due to CTC speciation, ozone decay to ?OH and the attractions between ionized CTC and TiO2 particles. The synergy effect in the UV/O3 and UV/TiO2/O3 process resulted in higher rates of reactions than sums of individual reaction rates. The TOC removal ranged from 8 to 41 % after 1 hour of reaction with the above mentioned order of efficiency.