The ultraviolet absorption spectrum, kinetics, and mechanism of the self reaction of CF₃CF₂O₂ radicals have been studied in the gas phase at 295 K. Two techniques were used; pulse radiolysis UV absorption to measure the spectrum and kinetics, and long‐path length FTIR spectroscopy to identify and quantify the reaction products. Absorption cross sections were quantified over the wavelength range 220–270 nm. At 230 nm, σ CF 3CF 2O 2 = (2.74 ± 0.46) ×10⁻¹⁸ cm² molecule⁻¹. This absorption cross section was used to derive the observed self reaction rate constant for reaction (1), defined as, −d[CF₃CF₂O₂]/dt = 2k_1obs[CF₃CF₂O₂]²: (Formula Presented.) k_1obs = (2.10 ± 0.38) ×10⁻¹² cm³ molecule⁻¹ s⁻¹ (2σ). The observed products following the self reaction of CF₃CF₂O₂ radicals were COF₂, CF₃O₃CF₃, CF₃O₃C₂F₅, and CF₃OH. CF₃O₂CF₃ was tentatively identified as a product. The carbon balance was 90–100%. The self reaction of CF₃CF₂O₂ radicals was found to proceed via one channel to produce CF₃CF₂O radicals which then decompose to give CF₃ radicals and COF₂. In the presence of O₂, CF₃ radicals are converted into CF₃O radicals. CF₃O radicals have several fates; self reaction to give CF₃O₂CF₃; reaction with CF₃O₂ radicals to give CF₃O₃CF₃; reaction with C₂F₅O₂ radicals to give CF₃O₃C₂F₅; or reaction with CF₃CF₂H to give CF₃OH. As part of this work a rate constant of (2.5 ± 0.6) ×10⁻¹⁶ cm³ molecule⁻s⁻¹ was measured for the reaction of Cl atoms with CF₃CHF₂ using a relative rate technique. Results are discussed with respect to the atmospheric chemistry of CF₃CF₂H (HFC‐125). © 1993 John Wiley & Sons, Inc.