Numerical modeling has been used to simulate different scenarios in sympathetic detonation studies. The objective of this project is to determine if the explosive will detonate due to shock waves or other phenomena. However, to predict the detonation of the explosive using this approach, an adequate reactive model of the explosive is required. The model includes the ignition and growth phases of the process due to shock initiation and detonation wave propagation in the explosive. In this study, a model was developed for cast H-6 explosive based on available experimental data from the literature. It contains three basic explosive properties: the un-reacted equation of state, the product equation of state, and the rate of reaction for the conversion of the solid explosive to reaction products. This model is available in the Lagrangian hydrodynamic computer codes LS-DYNA as an equation of state (EOS) and has been used in the numerical modeling of sympathetic detonation. One-dimensional calculations have also been performed and the results obtained agree well with experimental results available.