Alkyl and alkylperoxy radicals originating from dimethyl ether have been studied in the gas phase at 296 K. A pulse radiolysis-UV absorption technique was used. Absorption cross-sections were quantified over the wavelength range 220-350 nm. At 230 nm, σ_CH3OCH2 = (4.2 ± 0.5) × 10^-18 cm² molecule^-1 has been obtained. Rate constants for the reaction of the alkylperoxy radical with NO and NO₂ were determined to be (9.1 ± 1.0) × 10^-12 cm³ molecule^-1 s^-1 and (7.9 ± 0.4) × 10^-12 cm³ molecule^-1 s^-1, respectively.