Refractive indices of aqueous solutions of sulfuric acid and sulfuric acid/nitric acid were measured at 365, 313, 308, 254, and 214 nm at 298 K. The solution concentrations were H2SO4/H2O: 88.6, 78.7, 63.0, 52.3, 39.8 wt % SA (sulfuric acid); H2SO4/HNO3/H2O: 50.3 SA 2.5 NA (nitric acid), 45.4 SA 5.1 NA, 41.9 SA 7.4 NA, 37.9 SA 10.4 NA wt %. Densities of the solutions were also measured at low temperatures in order to calculate the refractive indices of these solutions at stratospheric temperatures. ¿ American Geophysical Union 1996