Absorption spectroscopy has been applied to low-pressure, self-deflagrating RDX flames in an attempt to refine the database for evaluation of detailed-chemistry combustion models. 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. Resultant absorption spectra of the B(2)Sigma(+) - X(2)Sigma(+) transitions for CN, A(3)II -X(3)Sigma(-) transitions for NH, and the A(2)Sigma(+) - (XII)-I-2 transitions for NO and OH were least-squares fitted to obtain best values for concentration and/or temperature. Peak CN mole fractions of about 200 ppm are obtained from "snapshot" absorption spectra of RDX burning in 1 atm air, mole fractions for NH are about a factor of 2 lower. As the pressure is increased, the CN and NH species peak closer to the combusting surface and reside over a smaller spatial extent. Peak concentrations drop for these higher pressures, but may be due, at least in part, to limitations of the spatial resolution of the pressurized absorption experiment chamber. Results from high-resolution absorption measurements instituted to overcome these limitations reveal CN concentrations of 140 ppm with more consistent peak positions, widths, and CN to NH peak ratios. Measurements of the concentration of NO species show a peak concentration of 25 mole-percent occurring at a position of 0.12 mm above the surface of the propellant. In the final flame region, measured OH concentrations of 1.7 mole-percent agree well with adiabatic calculations performed with the NASA-Lewis thermochemical equilibrium code. Calculated profiles of NO and OH are in good agreement with these measurements. Thr model peak positions and relative concentrations of CN and NH are also in good agreement with experiment. During the course of these spectroscopic measurements, burning rates for RDX over a pressure range of 1 to 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.