A comprehensive numerical analysis has been developed to predict the burning characteristics and detailed combustion wave structure of RDX/GAP/BTTN pseudo-propellant over a broad rang of pressures. The present work extends an existing model for the steady-state combustion of RDX/GAP pseudo-propellant to include the salient features of BTTN, a commonly used plasticizer for practical solid propellants. The entire combustion zone is divided into the solid-phase, subsurface multiphase, and gas-phase regions. In the solid-phase region, the constituent ingredients are physically linked to-ether and heated by conduction. Five global decomposition reactions, as well as subsequent reactions of RDX, GAP, and BTTN, are considered in the near-surface multiphase region. The overall gas-phase kinetics considers 72 species and 429 reactions in describing the heat-release mechanism. Good agreement is obtained with measured burning rates in the pressure range of 1-100 atm. The propellant surface temperature matches closely with the measured value and depends strongly on the RDX evaporation. The burning rate of RDX/GAP/BTTN is in general higher than that of RDX/GAP, a phenomenon that may be attributed to the stoichiometrically balanced nature of BTTN. (c) 2005 The Combustion Institute. Published by Elsevier Inc. All rights reserved.