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Pulse radiolysis and FT-IR smog chamber experiments were used to investigate the atmospheric fate of C₆H₅O(•) radicals. Pulse radiolysis experiments gave σ(C₆H₅O(•))_235 nm = (3.82 ± 0.48) × 10^-17 cm² molecule^-1, k(C₆H₅O(•) + NO) = (1.88 ± 0.16) × 10^-12, and k(C₆H₅O(•) + NO₂) = (2.08 ± 0.15) × 10^-12 cm³ molecule^-1 s^-1 at 296 K in 1000 mbar of SF₆ diluent. No discernible reaction of C₆H₅O(•) radicals with O₂ was observed in smog chamber experiments, and we derive an upper limit of k(C₆H₅O(•) + O₂) < 5 × 10^-21 cm³ molecule^-1 s^-1 at 296 K. These results imply that the atmospheric fate of phenoxy radicals in urban air masses is reaction with NO_x. Density functional calculations and gas chromatography−mass spectrometry are used to identify 4-phenoxyphenol as the major product of the self-reaction of C₆H₅O(•) radicals. As part of this study, relative rate techniques were used to measure rate …