Cavity ring-down spectroscopy combined with pulsed laser photolysis has been used to study the near-ultraviolet absorption spectrum (375-410 nm, (2) over tilde B-2(1) <-- (X) over tilde B-2(1) transition) of the phenoxyl radical (C6H5O.) in 10-20 Torr of nitrogen diluent at 298 K. By using a numerical fitting routine on the basis of a modeling of chemical reaction system, the absorption cross section of the phenoxyl radical was obtained, sigma = (7.7 +/- 2.3) x 10(-18) cm(2) molecule(-1) (base e) at 394.4 nm. A spectrum simulation was carried out using available Franck-Condon integrals with a 400 cm(-1) Lorentzian line width, which suggests a short-lived excited state. Time-dependent density functional theory (TD-UB3LYP/aug-cc-pVTZ) calculations supported the interpretation of the absorption band for the phenoxyl radical. The rate constant of the phenoxyl radicals with methyl radicals was derived, k(C6H5O+ CH3) = (6.2 +/- 2.6) x 10(-11) cm(3) molecule(-1) s(-1), at 298 K in 20 Torr of nitrogen diluent.