Abstract Theoretical investigations were carried out on the mechanism, kinetics and thermochemistry of the gas-phase reactions between CHF 2 CF 2 OCHF 2 and OH radical using the high level ab initio G2(MP2) and hybrid density functional MPWB1K/6-31+G(d,p) methods. Two most stable conformers of CHF 2 CF 2 OCHF 2 are identified and the energy difference between them is found to be only 0.3 kcal mol −1 . Both of them are considered for rate coefficient calculations in our study and the contribution from each of the conformers is found to be quite significant in the temperature range of our study. The rate coefficients are determined for the first time in a wide range of temperature 250–1000 K. The calculated total rate coefficient value k OH = 1.01 × 10 −15 cm 3 molecule −1 s −1 is in reasonably good agreement with the experimental value of k OH = 2.36 × 10 −15 cm 3 molecule −1 s −1 at 298 K. The heats of formation for CHF 2 CF 2 OCHF 2 and CHF 2 CF 2 OCF 2 and CF 2 CF 2 OCHF 2 radicals are estimated to be −359.64, −305.43 and −306.88 kcal mol −1 , respectively. The bond dissociation energies of the two C–H bonds are CHF 2 CF 2 OC(–H)F 2 : 106.3 kcal mol −1 and C(–H)F 2 CF 2 OCHF 2 : 104.8 kcal mol −1 . The atmospheric lifetime of CHF 2 OCF 2 CHF 2 is estimated to be around 35 years.