Rhodium catalyzed hydrogenation is a chemical reaction that typically involves the addition of pairs of hydrogen atoms to another compound or element in the presence of a Rhodium complex catalyst. The addition of hydrogen to double or triple bonds in hydrocarbons is a type of redox reaction that can be thermodynamically favorable without a catalyst. For example, the addition of hydrogen to an alkene has a Gibbs free energy change of -101kJ mol-1.[1] However, the reaction rate for most hydrogenation reactions is negligible without extremely high temperatures or pressures. Rhodium (Rh) is a transition metal, and the complexes it can form act as catalysts to allow hydrogenation and other chemical reactions to occur at lower temperatures and lower pressures. The rhodium complex catalyst is able to bind both the unsaturated substrate as well as the H2 in order to facilitate the transfer of hydrogen to substrate. Other transition metals such as platinum, palladium, and nickel can also act as catalysts in the hydrogenation process.