Pacific Scientific Energetic Materials Co. (PacSci EMC) in Chandler, AZ, in conjunction with the Office of Naval Research, has recently been involved in a program to develop existing or new materials which would serve as replacements for tetrazene and which have improved thermal and hydrolytic stability while maintaining the high sensitivity levels required. PacSci EMC has completed initial testing on a variety of compounds and has identified a new material which meets these qualifications. This material, MTX-1, is easily and inexpensively prepared from tetrazene in one step in aqueous solution. Side by side TGA studies on tetrazene (DSC exo 144°C) and MTX-1 (DSC exo 214°C) demonstrate that at 90°C, tetrazene loses 36% by weight over 167 hours while MTX-1 loses only 4% during the same time period. In addition, it has been determined that after exposure to water for ~120 days, MTX-1 may be re-isolated unchanged and in nearly quantitative yield. Most importantly, MTX-1 has safety characteristics (impact, friction, ESD) which are comparable to those of tetrazene and provides nearly equivalent (ball drop) sensitization of 95% BLS mixes when compared to identical mixes made with tetrazene. Although the crystal habit of MTX-1 is already very similar to that of tetrazene, additional process modifications may provide a larger (and more sensitive) morphology. MTX-1 is currently under investigation at PacSci EMC as a research and development material.