What is "hydrogenolysis"

n. (context chemistry English) the cleavage of a molecule, especially that of a carbon-carbon bond, with the addition of hydrogen atoms to the fragments

Hydrogenolysis is a chemical reaction whereby a carbon–carbon or carbon– heteroatom single bond is cleaved or undergoes lysis (breakdown) by hydrogen. The heteroatom may vary, but it usually is oxygen, nitrogen, or sulfur. A related reaction is hydrogenation, where hydrogen is added to the molecule, without cleaving bonds. Usually hydrogenolysis is conducted catalytically using hydrogen gas.