The methoxymethyl radical, CH3OCH2, formed from the photodissociation of CH3OCH2Br at 248 nm, was observed to form OH on reaction with O-2. The kinetics of OH formation were measured as a function of pressure at 295 K using this new photolytic methoxymethyl radical precursor, detecting OH by LIF, giving rate coefficients in good agreement with the literature values for CH3OCH2 + O-2 (R2). This reaction proceeds via the formation of an energised CH3OCH2O2 adduct, which either dissociates to OH + 2H(2)CO or is collisionally stabilised. To quantify OH production from the CH3OCH2 + O-2 reaction, both relative and absolute OH yield measurements were performed as a function of pressure. (C) 2010 Elsevier B.V. All rights reserved.