The photocatalytic cleavage of the C–F bond in pentafluorophenol (PFP) with ZnO using 254 and 365 nm UV light has been investigated under different conditions. The defluoridation was monitored using an ionometer with a fluoride ion selective electrode. The photocleavage was more effective under 254 nm than under 365 nm UV light. With 254 nm UV light, TiO₂-P25, TiO₂ (anatase), ZnO, and ZrO₂ photocatalyzed the deflouridation of PFP, whereas CdS, CdO, and SnO₂ did not. The defluoridation is enhanced by the addition of oxidants such as KIO₄, KClO₃, (NH₄)₂S₂O₈, and KBrO₃. The periodate ion is found to be the most efficient oxidant. The defluoridation intermediates were found to be tetrafluorodihydroxybenzene, trifluorotrihydroxybenzene, and tetrafluoroquinone