Rate constants for the reactions of cyc-CF2CF2CF2CHFCH2- (k(1)) and trans-cyc-CF2CF2CF2CHFCHF- (k(2)) with OH radicals were assessed by a relative rate method. The values were determined as (9.35 + 5.83) x 10(-13) exp[-(1197 + 180)/T] and (8.02 + 2.17) x 10(-13) exp[-(1198 + 80)/T] between 253 and 328K; and (1.72 +/- 0.05) x 10(-14) and (1.43 +/- 0.03) x 10(-14) cm(3) molecule(-1) s(-1) at 298K, respectively. The atmospheric lifetimes were 2.8 and 3.2 years; the 100-year time horizon global warming potentials were estimated to be 211 and 241, respectively. (C) 2015 Elsevier B.V. All rights reserved.