The rate constant k for the gas-phase reaction of atomic hydrogen with 1,1,2,3,4,4-hexafluoro-1,3-butadiene has been measured over the temperature range 290-1010 K by time-resolved atomic resonance fluorescence using H2O and NH3 as precursors, at argon pressures of about 30-140 mbar, Over the range 290-620 K a positive activation energy was observed, k = (3.40 +/-0.34) x 10(-11) exp[(-16.7 +/- 0.4) kJ mol(-1)/RT] cm(3) molecule(-1) s(-1), and k dropped rapidly between 620 and 700 K. Over the range 700-1010 K, k = (1.83 +/- 0.53) x 10(-10) exp[(-34.1 +/- 2.1) kJ mol(-1)/RT] cm(3) molecule(-1) s(-1) where the statistical uncertainties are 1 sigma. Confidence limits for k are +/- 16%. Several isomers Of C4F6H were characterized by ab initio methods, Below about 600 K the dominant pathway is suggested to be addition of H atoms to form CF2H-CF . -CF=CF2 and/or CF2H-CF . -CF=CF2. These adducts dissociate at elevated temperatures, and on the assumption that the major addition product at around 670 K is the more stable CF2H-CF . -CF=CF2, the C-H bond dissociation enthalpy is estimated via a third-law method to be about -111 kJ mol(-1), with an estimated uncertainty of 7 kJ mol(-1).