Heterogeneous reactive materials are relevant for a variety of scientific and engineering fields. Modeling these complicated systems often requires highly advanced mathematical models, cutting edge numerical algorithms and implementations, and intensive calibration thereof. Much effort has been made in accomplishing these tasks. This has led to a great deal of progress in the modeling and simulation of these material systems which, in turn, has led to vast improvements in the physical understanding of the various mechanisms at play. However, these efforts are often limited by issues with thermodynamic consistency, the inherent nonlinearity of the relevant fields of interest (chemical species, temperature, deformation, etc.), and complex physical coupling between said fields.To this end, this dissertation develops a chemo-thermal-mechanical model that considers phase transition phenomena, heat generation due to chemical reactions and mechanical deformations, and finite strain elasto-plastic behavior. The dissertation also develops numerical algorithms for the computational implementation of the model which are developed as a state-of-the-art finite element solver. The model is calibrated using available experimental data, then applied to the β→δ phase transition of single crystal HMX as well as to HMX based PBXs.