Abstract : In an attempt to refine the database for the evaluation of detailed-chemistry combustion models, absorption spectroscopy has been applied to low pressure, self-deflagrating RDX flames. Semi-empirically determined production rates of reactants from the solid propellant surface, together with a detailed gas-phase elementary reaction set, were used to develop a model that minimizes the effect of uncertainties in the description of solid phase processes. The spatial profiles of two low concentration, highly reactive, short-lived diatomic species, CN and NH, were obtained at pressures varying from 1 to 2 atm in air. Two major species, NO and OH, were also profiled using this technique. The CN and NH profiles agree well with previous measurements and the current model. NO and OH profiles are also in good agreement with the models. During the course of these spectroscopic measurements, burning rates for RDX over a pressure range of 1-2 atm have also been determined. These values range from 0.23 mm/s at atmospheric pressure to 0.50 mm/s for 2 atm and are noticeably lower than some of the other published measurements. Calculations stemming from the proposed model predict a burning rate of 0.29 mm/s and 0.54 mm/s for the same pressure levels.