The ultraviolet absorption spectrum of FO₂ radicals and the kinetics of the reaction of F atoms with O₂ have been studied in the gas phase at 295 K using pulse radiolysis combined with kinetic UV spectroscopy. At 230 nm, σ_FO2 =(5.08±0.70)×10^-18 cm² molecule^-1. The kinetics of the reaction F+O₂+M→FO₂+M (1), were investigated over the pressure range 200-1000 mbar of SF₆ diluent. At 1 atm total pressure the pseudo-second-order rate constant for reaction (1) was determined to be (1.9±0.3)×10^-13 cm³ molecule^-1 s^-1.