Relative rate techniques were used to estimate k(OH+HFE-7100) ≈ 1.2 × 10^-14 cm³ molecule^-1 s^-1 at 295 K leading to an estimate of ≈5 years for the atmospheric lifetime of HFE-7100 (HFE = hydrofluoroether). Pulse radiolysis transient UV absorption spectroscopy was used to study the ultraviolet absorption spectra and kinetics of C₄F₉OCH₂ and C₄F₉OCH₂O₂ radicals at 296 K. At 300 nm σ(C₄F₉OCH₂) = (5.80 ± 0.76) × 10^-19 and at 250 nm σ(C₄F₉OCH₂O₂) = (2.24 ± 0.24) × 10^-18 cm² molecule^-1. Both UV spectra showed two absorption maxima, one below 230 nm and one at 290 nm. Rate constants for the self-reactions of C₄F₉OCH₂ and C₄F₉OCH₂O₂ radicals, the reaction of C₄F₉OCH₂ radicals with O₂, and the reactions of C₄F₉OCH₂O₂ radicals with NO and NO₂ were (3.5 ± 0.8) × 10^-11, (1.35 ± 0.17) × 10^-11 (uncorrected for possible secondary chemistry), (2.5 ± 0.5) × 10^-12, (8.5 ± 2.5) × 10^-12, and (8.8 ± 1.8) × 10^-12 cm³ molecule^-1 s^-1, respectively. Using a pulse radiolysis method we measured k(F+HFE-7100) = (1.6 ± 0.6) × 10^-11 cm³ molecule^-1 s^-1. Using a Fourier transform infrared spectroscopic technique rate, constants for the reaction of F and Cl atoms with HFE-7100 and Cl atoms with C₄F₉OC(O)H were determined to be (1.3 ± 0.3) × 10^-11, (9.7 ± 1.4) × 10^-14, and (1.6 ± 0.7) × 10^-14 cm³ molecule^-1 s^-1, respectively. Finally, it was determined that the sole atmospheric fate of C₄F₉OCH₂O• radicals is reaction with O₂ to give C₄F₉OC(O)H (perfluorobutyl formate). The results are discussed with respect to the atmospheric chemistry of HFE-7100.