A system for rejecting heat from equipment using endothermic isomerization. includes a heat exchanger configured to receive an elevated-temperature process fluid and an isomerization compound capable of endothermic isomerization. When the system is in operation, heat from the elevated temperature process fluid is transferred to the isomerization compound and the isomerization compound endothermically isomerizes to a higher energy state form. A vehicle includes an engine and a body. The body houses a catalytic heat exchanger having an output in fluid communication with the engine, a pump for urging an isomerization compound into the heat exchanger, and a heat sink controller for controlling the pump. A method for rejecting heat from equipment using endothermic isomerization includes providing a compound capable of endothermic isomerization and transferring heat from a process fluid to the compound, such that the compound endothermically isomerizes to a higher energy level isomer.