A two-dimensional meridional model of negative ions in the stratosphere is presented. It indicates that NO3- and HSO4- core ions with HNO3 and H2SO4 ligands are the most abundant negative ions in this region of the atmosphere. In accordance with observations at 44 ¿N the model predicts a sharp changeover of HSO4- core ions over NO3- core ions at about 32 km. It also predicts a reverse changeover at 42 km above which NO3- core ions again become dominant. For other latitudes no comparison can be made due to the lack of observational data. The negative ion composition appears to be determined by sulfuric acid vapor and nitric acid concentrations. The sensitivity of the ion composition model to the concentration of these acids is discussed. Finally, the meridional distributions of major negative ions are presented. A companion paper on positive ions is presented by Beig et al. (this issue). ¿ American Geophysical Union 1992