The quantum yield for the production of NO3 in the N2O5 photolysis at 248 nm was measured to be unity. The concentration of NO3 produced upon photolysis was measured using 662‐nm laser absorption. The quantum yields for O(3P) production in the photolysis of N2O5 at 248 nm, 266 nm, 287 nm, and 289 nm were also measured using resonance fluorescence detection of O(3P). The quantum yield for O(3P) decreased from 0.7 at 248 nm to 0.15 at 289 nm. It is postulated that N2O5 photolysis at wavelengths less than 298 nm yields NO3 + NO + O(3P)in addition to NO3 + NO2.