The ultraviolet spectra of aqueous nitrite and nitrate solutions and of binary mixtures were obtained. By using an addition technique and a reference nitrate/nitrite solution it was possible to compensate for the interference caused by the overlapping of the nitrate and nitrite bands, which is normally a limiting factor in the analysis of mixtures of nitrite with large excesses of nitrate. The detection limit was 5 × 10−5M NO2−which corresponded to a minimum detectable amount of 2.3 ppm NO2−in the presence of up to 20,000 times greater amount of NO3−. The accuracy was ± 0.6% and the standard deviation ± 0. 002.