a colourless, easily liquefied, gaseous hydrocarbon (compound of carbon and hydrogen), the third member of the paraffin series following methane and ethane. The chemical formula for propane is C₃H₈. It is separated in large quantities from natural gas, light crude oil (petroleum), and oil-refinery gases and is commercially available as liquefied propane or as a major constituent of liquefied petroleum gas (LPG).

As with ethane and other paraffin hydrocarbons, propane is an important raw material for the ethylene petrochemical industry. The decomposition of propane in hot tubes to form ethylene also yields another important product, propylene. From propylene such organic chemicals as acetone and propylene glycol are derived. The oxidation of propane to such compounds of carbon, hydrogen, and oxygen as acetaldehyde is also of commercial interest.

Although a gas at ordinary atmospheric pressure, propane has a boiling point of -42.1° C (−43.8° F) and thus is readily liquefied under elevated pressures. It therefore is transported and handled as a liquid in cylinders and tanks. In this form, alone or mixed with liquid butane, it has great importance as a fuel for domestic and industrial uses and for internal-combustion engines.