BACKGROUND; In this study, simultaneous photocatalytic degradation of four fluoroquinolone (FQ) compounds (i.e. ofloxacin, norfloxacin, ciprofloxacin and enrofloxacin) was investigated in TiO2 suspensions under simulated solar light irradiation. Effects of experimental variables including pH, TiO2 dosage, initial substrate concentration and hydrogen peroxide (H2O2) on the degradation processes were also investigated. RESULTS: The antibiotics degradation was pH-influenced. The photocatalytic reaction followed the pseudo-first-order model, with reaction rate constants (k) 0.026, 0.027, 0.022 and 0.026 min(-1) for ofloxacin, norfloxacin, ciprofloxacin and enrofloxacin, respectively. Complete elimination of four FQswas achieved in a reaction system composed of 0.5 g L-1 of TiO2 and 82.5mg L-1 of H2O2 at pH 6 after 90 min irradiation. Mineralization of FQs during TiO2 photocatalysis was slower than the FQs conversion, and the antibacterial activity of the four FQs was completely removed by TiO2 under simulated solar light irradiation. CONCLUSION: The four FQs can be simultaneously degraded andmineralized with commercially available TiO2 under simulated solar light irradiation. Microbiological analysis showed that the antibacterial activity of the four FQs was completely removed. These results are helpful for antibiotics removal in the environment, and for exploring new technology for wastewater treatment. (C) 2012 Society of Chemical Industry