1) Forensic Explosives Laboratory, Dstl, Fort Halstead, Sevenoaks, Kent TN14 7BP, UK, 2) Stable Isotope Forensics Facility, Environ. Eng. Res. Centre, S.P.A.C.E., Queen’s University Belfast, David Keir Building, Belfast BT9 5AG, UK Forensic Science International (2008), V179, pp157–162, doi:10.1016/j.forsciint.2008.05.015 Investigation of isotopic linkage between precursor and product in the synthesis of a high explosive Claire M. Lock (1) and Wolfram Meier-Augenstein (2) In criminal proceedings involving illegally manufactured substances, evidence demonstrating the manufacture is required for successful prosecution. In many circumstances the presence of manufacturing equipment and ‘recipes’ are clear indicators. However establishing chemical links between starting materials and products would be beneficial additional evidence in such circumstances. We report here the results of an isotope study investigating a link between hexamine used as a starting material and the product explosive RDX, manufactured using the Woolwich process. Isotopic composition of hexamine and RDX was analysed by stable isotope ratio mass spectrometry. Five different hexamine samples were selected from a group of eleven for use in this study. One of the five hexamine samples was used twice, providing data on the reproducibility of the synthesis. Carbon and nitrogen isotope analysis of the hexamine starting material and RDX products reveals a reproducible relationship between reactant and product.