Hydrogenation is a chemical reaction between molecular Hydrogen (H2) and another Compound or Element, usually in the presence of a Catalyst such as Nickel, Palladium or Platinum. The process is commonly employed to reduce or saturate Organic Compounds. Hydrogenation typically constitutes the addition of pairs of Hydrogen atoms to a molecule, often an Alkene. Catalysts are required for the reaction to be usable; Non-Catalytic Hydrogenation takes place only at very high temperatures. Hydrogenation reduces double and triple bonds in Hydrocarbons.