Biomarkers are organic molecules found in the natural environment whose stable carbon skeletons have been well preserved. They are often regarded, therefore as "chemical fossils" and can provide valuable information about the biological origins and subsequent transformations undergone by organic matter in the natural environment and geosphere. Although biological sources have been identified for many lipids in environmental samples, the gaps in our knowledge are large. We propose to utilise the unique capabilities of hydropyrolysis (pyrolysis assisted by high hydrogen pressures) to generate representative biomarker hydrocarbon profiles (both free and bound) from a broad range of microorganism species. This will facilitate more accurate chemotaxonomny to be performed in earth and aquatic applications. The findings of this project will be of great interest to all disciplines which employ biomarker lipids as diagnostic molecular tools.