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Abstract. The mechanisms of molecular halogen production from frozen saline surfacesremain incompletely understood, limiting our ability to predict atmosphericoxidation and composition in polar regions. In this laboratory study,condensed-phase hydroxyl radicals (OH) were photochemically generated infrozen saltwater solutions that mimicked the ionic composition of oceanwater. These hydroxyl radicals were found to oxidize Cl−, Br−, andI−, leading to the release of Cl2, Br2, I2, and IBr. Atmoderately acidic pH (buffered between 4.5 and 4.8), irradiation of icecontaining OH precursors (either of hydrogen peroxide or nitrite ion)produced elevated amounts of I2. Subsequent addition of O3produced additional I2, as well as small amounts of Br2. At lowerpH (1.7–2.2) and in the presence of an OH precursor, rapid dark conversionof I− to I2 occurred from reactions with hydrogen peroxide ornitrite, followed by substantial photochemical production of Br2 uponirradiation. Exposure to O3 under these low pH conditions alsoincreased production of Br2 and I2; this likely results fromdirect O3 reactions with halides, as well as the production ofgas-phase HOBr and HOI that subsequently diffuse to frozen solution to reactwith Br− and I−. Photochemical production of Cl2 was onlyobserved when the irradiated sample was composed of high-purity NaCl andhydrogen peroxide (acting as the OH precursor) at pH = 1.8. Thoughcondensed-phase OH was shown to produce Cl2 in this study, kineticscalculations suggest that heterogeneous recycling chemistry may be equallyor more important for Cl2 production in the Arctic atmosphere. Thecondensed-phase OH-mediated halogen production mechanisms demonstrated hereare consistent with those proposed from recent Arctic field observations ofmolecular halogen production from snowpacks. These reactions, even if slow,may be important for providing seed halogens to the Arctic atmosphere. Ourresults suggest the observed molecular halogen products are dependent on therelative concentrations of halides at the ice surface, as we only observewhat diffuses to the air–surface interface.