Fourier transform infrared smog chamber techniques were used to study the kinetics and mechanisms of the reactions of Cl atoms and OH radicals with pentafluorophenol (C₆F₅OH) in 700 Torr total pressure of air or N₂ diluent at 296 ± 2 K. Rate constants k(OH + C₆F₅OH) = (6.88 ± 1.37) × 10^-12 cm³ molecule^-1 s^-1 and k(Cl + C₆F₅OH) = (2.52 ± 0.31) × 10^-11 cm³ s^-1 molecule^-1 in 700 Torr air diluent were determined. In 700 Torr N₂, the rate constant for the reaction of C₆F₅OH with Cl atoms is linearly dependent on the Cl atom concentration. Product studies on this reaction in both 700 Torr air and 700 Torr N₂ diluent show the formation of nonconjugated products. The photolysis constant of C₆F₅OH was determined by 254 nm UV irradiation of a C₆F₅OH and CH₃CHO mixture in 700 Torr air or N₂ at 296 ± 2 K and yielded a photolysis rate constant of J(C₆F₅OH) = (2.83 ± 0.25) × 10^-3 s^-1. Results are discussed with respect to the atmospheric chemistry of other halogenated aromatic species.