As new fuels are introduced into the energy infrastructure, the issue of chemical stability of arises in numerous contexts. For example, in the development of next-generation rocket kerosenes, thermal stability is critical because the liquid is used as a high-temperature heat sink before being burned in the engine. The development of next-generation hypersonic vehicles is hampered because of the need to use the fuel as a moderate- to high-temperature heat sink, as well. The serious issues of biofuel degradation (thermal and oxidative) are well known. We approach the study of thermal decomposition in two ways. First, we have developed an ampoule-based global decomposition kinetics protocol that provides the pseudo-first order rate constant (with Arrhenius parameters and activation energies) for complex fluids such as kerosenes. This has been used to measure decomposition, evaluate and design stabilizers, and to study reaction mechanism. This work is unique because in collaboration with shock tube researchers, we have developed the world’s longest Arrhenius plot (over 11 orders of magnitude). We also have developed continuous process reactors to generate sufficient quantities of thermally stressed fuels so that a full range of property measurements can be performed. Our facility includes a complete, state of the art chemical analysis capability. The two approaches are being used to advance the field of high stress fuels and fluids, but much more needs to be done, especially with the growing suite of renewable fluids entering the market.