A pulse radiolysis technique was used to study the UV absorption spectrum of CF₃CF₂CFHO₂ radicals (at 250 nm σ = (175 ± 36) × 10^-20 cm² molecule^-1). The observed bimolecular rate constant for the self reaction of CF₃CF₂CFHO₂ radicals was k_13obs = (5.2 ± 1.4) × 10^-12 cm³ molecule^-1 s^-1. Rate constants for reactions of CF₃CF₂CFHO₂ radicals with NO and NO₂ were k₃ > × 10^-12 and k₄ = (6.3 ± 0.7) × 10^-12 cm³ molecule^-1 s^-1, respectively. Using a FTIR spectrometer/smog chamber technique it was shown that, under atmospheric conditions, reaction with O₂ and decomposition via C-C bond scission are competing loss mechanisms for CF₃CF₂CFHO radicals. A lower limit of 10⁵ s^-1 was deduced for the rate of decomposition of CF₃CF₂CFHO radicals via C-C bond scission at 296 K in 1 bar of SF₆ diluent. It is estimated that in the atmosphere approximately 98% of CF₃CF₂CFHO radicals will undergo decomposition into C₂F₅ radicals and HC(O)F and 2% will react with O₂ to give C₂F₅C(O)F. As part of this work relative rate methods were used to measure rate constants of (1.3 ± 0.3) × 10^-12 and (1.5 ± 0.3) × 10^-15 cm³ molecule^-1 s^-1 for the reactions of CF₃CF₂CFH₂ with F and Cl atoms, respectively.