HHC stands for hexahydrocannabinol, which is a hydrogenated form of THC. HHC is formed when hydrogen atoms are added to THC using a catalyst, such as nickel or palladium, and high pressure. The process breaks the double bond in THC, and then forms HHC. Scientist have discovered at least 10 isomers of HHC since it was first identified in the 1940’s.