Hydrogenolysis is a catalytic chemical reaction whereby a molecule of hydrogen is added over a carbon-heteroatom single bond, effectively causing a "lysis" of the bond. The heteroatom may vary, but usually is oxygen, nitrogen or sulfur. A closely related reaction is hydrogenation, where hydrogen is added over a carbon-carbon double bond (leading to the ultimate reduction to a single bond).
A classic example of hydrogenolysis is debenzylation - the removal of a benzyl protecting group usually attached to an oxygen or a nitrogen atom .
With the current knowledge, the only definitive statement that can be made about the ease of hydrogenolysis is that presence of a positive charge (formal or partial) on the heteroatom greatly increases the rate of hydrogenolysis. A proposed mechanism is presented in the hydrogenation article.
A commercial large-scale example of hydrogenolysis is the Raney Nickel catalyzed "desulfurization" of substituted thiophene rings, which is a general method for the synthesis of certain hydrocarbons.
The term was coined by Homer Burton Adkins.