Using the discharge flow method with detection of species by mass spectrometry and laser-induced fluorescence, the kinetics of the reaction BrO + CH3O2 → products has been studied at 298 K. The rate constant obtained is (5.7±0.6) × 10−12 cm³ molecule−1 s−1. The mechanism of the reaction has been also investigated. These laboratory data are used to discuss the possible impact of this reaction on the ozone budget in different parts of the atmosphere. The reaction is likely to be negligible in the stratosphere, but is potentially significant in the remote marine boundary layer. The BrO+CH3O2 reaction, together with other BrO+RO2 reactions, may also significantly contribute to the ozone loss events observed in the Arctic troposphere in spring.