This paper aimed at illustrating the impact of catalytic ozonation on trihalomethane formation potential (THMsFP) of a filtered surface water. Catalytic ozonation with several metal oxides (synthetic α-FeOOH (FeOOH), γ·Al2O3 (Al2O3), CeO2 and MgO) significantly reduced THMsFP of the water compared with ozonation alone. For the FeOOH catalyzed ozonation, several factors, including bromide concentration, pH, alkalinity, ozone dosage, and reaction time, were further studied for their effect on THMsFP of the water. The FeOOH/O3 showed a significant advantage over ozonation in controlling the THMsFP at the applied conditions of bromide (0-3.36 mg/L), pH (6.33-9.43), O3/DOC ratio (0.65-2.05 mg/mg), and reaction time (2-20 min). Increase of bicarbonate alkalinity weakened its advantage. The possible mechanism for the FeOOH/O 3 in controlling the THMsFP can be ascribed to higher DOC removal rate and enhanced oxidation of some precursors.