Aldehydes and ketones are reduced to alcohols through catalytic hydrogenation, typically using hydrogen gas (H2) and a metal catalyst. Common catalysts include platinum (Pt), palladium (Pd), or nickel (Ni). During catalytic hydrogenation, the carbonyl group undergoes addition of hydrogen, resulting in the reduction of the carbon-oxygen double bond to form the corresponding alcohol. The metal catalyst facilitates the activation of hydrogen and promotes the reaction. This method provides a mild and selective way to convert aldehydes and ketones to alcohols without affecting other functional groups present in the molecule.