The potential energy surface of the C 2 HF 2 O and C 2 F 3 O radicals were computed at the B3LYP density functional and the CCSD(T) ab initio levels of theory. For C 2 HF 2 O radical, the resonance dominating methyl radical (HFC -CF O) is found to the most stable isomer, followed by the difluoro acetyl ([F 2 HCC O] ) isomer by 9.9kcal/mol. However, the most stable C 2 F 3 O radical isomer is trifluoro acetyl radical ([F 3 CC O] ), followed by the methyl isomer (F 2 C -CF O) by 1.8kcal/mol. Both acetyl radicals are relatively stable towards dissociation of being endothermic with low barriers, while other transformations (cyclization, hydrogen, and fluorine arrangements) are endothermic and have very high barriers.