The atmospheric oxidation mechanisms of E143a (CF,OCH,), E134 (CHF2OCHF2), and E125 (CHF2OCF3) have been investigated using experimental and ab initio methodology. The oxidation of E143a produces the stable reservoir species trifluoromethyl formate, CF3OCOH, which further oxidizes to CF2O and CO2. Oxidation of E134 and E125 shows the presence of only CF2O under the condition of high O-2 concentrations. Carbonyl fluoride can be formed from two competing pathways involving the halogenated alkyl radicals formed from hydrogen abstraction of E134 and E125. CO bond fission reactions and O-2 addition reactions compete to produce carbonyl fluoride and a CFxH3-x radical fragment. Computational modeling of the reaction pathways provides insight into the molecular steps of the degradation process.