Thermal decomposition of CnF2n+1CO (n = 1-3) radicals was investigated using RRKM/ME calculations, with geometrical parameters and energetics determined at the G(2)M//MPW1K and CBS-QB3 levels. The decomposition rate constant of CnF2n+1CO increases with increasing carbon chain length. In the atmosphere, decomposition Of C3F7CO competes with a reaction with 02 that produces C3F7C(O)O-2. The decomposition fraction of C3F7CO is calculated to be 73% and 50% at the G2M//MPW1K and CBS-QB3 levels under ambient conditions, whereas that of CF3CO is 1%. The yields of CnF2n+1C(O)OH, formed by the reaction of CnF2n+1C(O)O-2 with HO2, are discussed using the obtained results. (c) 2006 Elsevier B.V. All rights reserved.