The development of weapons that can travel at hypersonic speeds is becoming a high priority to the US Air Force. A key technology needed for the continued development of these propulsion systems is the ability to cool the combustor by flowing fuel through channels machined in the walls. Currently, the cooling capacity of kerosene-based fuels is relatively low even with endothermic cracking reactions, and this limits the Mach number that can be achieved. Moreover, increasing the fuel cooling capacity by raising the fuel flow is not practical because the additional fuel would over-fuel the combustor or have to be dumped overboard. Likewise, allowing the fuel to reach higher temperatures is not feasible because coke formation could lead to heat exchanger failure. Therefore, there is a strong need to develop new endothermic fuels and custom heat exchanger/reactors that can deliver substantially higher heat sink capacities. Under a very successful Phase I project with the US Air Force, Reaction Systems has identified a fuel and catalyst combination that can undergo a chemical reaction that produces much higher endotherms than currently available with kerosene-based fuels. In addition, Reaction Systems has just been notified of a Phase II award to continue development of the fuel/catalyst system and design a custom heat exchanger/reactor for use in a hypersonic engine.