The kinetics of the reaction OH+HNO3 k2→ products has been studied over the temperature range 224--366 K. OH radicals were produced by pulsed (laser or flash lamp) photolysis of HNO3. The course of the reaction was monitored by detecting OH using the resonance fluorescence technique. A total of 27 bimolecular rate constants (derived from 150 individual experiments) were determined under varying conditions of temperature, pressure, photolysis photon flux and wavelength, diluent gas identity, and flow rate. In all experiments the HNO3 concentration was constantly monitored by 184.9-nm absorption. The data are best described by the following Arrhenius expression: k2 = (1.52¿0.38)¿10-14exp<(+649¿69)/T>cm3 molecule1 s1. The stratospheric implications of these new rate data have been assessed by using a one-dimensional transport-kinetic model. Reductions in O3 depletion due to chlorofluoromethane release and NOx injection are calculated. The magnitude of these reductions is strongly dependent on the identity of the reaction products.