Theoretical studies have been performed on the kinetics, mechanism and thermochemistry of the hydrogen abstraction reactions of CF3CF2OCH3 (HFE-245mc) and CF3CF2OCHO with OH radical using DFT based M06-2X method. IRC calculation shows that both hydrogen abstraction reactions proceed via weakly bound hydrogen-bonded complex preceding to the formation of transition state. The rate coefficients calculated by canonical transition state theory along with Eckart's tunnelling correction at 298 K: k(1)(CF3CF2OCH3 + OH) = 1.09 x 10(-14) and k(2)(CF3CF2OCHO + OH) = 1.03 x 10(-14) cm(3) molecule(-1) s(-1) are in very good agreement with the experimental values. The atmospheric implications of CF3CF2OCH3 and CF3CF2OCHO are also discussed. (C) 2016 Elsevier B.V. All rights reserved.