Hydrogenation is a chemical reaction, typically in the presence of a catalyst such as nickel, palladium or platinum, between molecular hydrogen and another compound or product. Commonly, the procedure is used to reduce or saturate organic compounds. Hydrogenation typically represents the addition of hydrogen atom pairs to a molecule, often an alkene. For the reaction to be functional catalysts are required; non-catalytic hydrogenation occurs only at very high temperatures. Hydrogenation reduces hydrocarbon bonds by doubles and triples. Hydrogenation consists of three components: unsaturated base, hydrogen (or source of hydrogen) and always a catalyst. The reduction reaction relies on the substrate and the operation of the catalyst, at varying temperatures and pressures.