This proposal seeks to identify and characterise high-pressure polymorphs of the energetic materials hydroxylammonium perchlorate, CL-20, diaminodinitroethene (FOX-7), and nitrotriazolone. The proposal will also investigate the response of intermolecular interactions in the crystal structures to high pressures. These studies will complement spectroscopic and X-ray diffraction measurements made in Edinburgh and at the SRS Daresbury Laboratory. The results will be of direct interest to those in the energetics community seeking to predict and model the properties and performance of these materials. Theorists in chemistry, physics and materials science will find the high-pressure data of crucial importance for testing ab initio crystal-structure predictions and molecular dynamics simulation.