Heterogeneous reactions involving sodium halide particles and gaseous ozone were investigated by reaction-chamber experiments in order to explore the possible role of sea-salt particles as a source of reactive halogen species in the troposphere. In the studies of sodium bromide and ozone, it was found that gaseous bromine molecules were produced in the presence of water vapor with which the salts were almost deliquesced. This preliminary result suggests that reactive bromine species can be released from sea-salt to the atmosphere of the marine boundary layer in the absence of nitrogen oxides. ¿ 1998 American Geophysical Union