The chemistry of the production of NO in the stratosphere was examined in a two part study. First, the absolute quantum yield for the production of NO(2&Pgr;)+N(4S) from N2O photolysis at 193 nm was measured to be less than 8¿10-3. Second, in a new type of experiment, the yields of NO from the photolysis of N2O at 193 nm in N2O/O2/N2 and the photolysis of O3 at 248 nm in O3/N2O/O2/N2 mixtures were measured. The measured yields showed excellent agreement with NO yields predicted from a model using previously measured rate parameters. The results of this ''integrated'' experiment reduced the most probable uncertainty in the yield of NO from near 80% (calculated from the uncertainties in each individual step) to less than 30%. ¿ American Geophysical Union 1990