Fischer-Tropsch is the most common process used to synthesize liquid fuels from on-oil sources (typically coal or natural gas).

Fischer-Tropsch reacts a mixture of carbon monoxide and hydrogen, in the presence of a catalyst, to form liquid hydrocarbons. The feedstock gas mixture (called synthesis gas) is formed by gasifying coal or natural gas.

Fischer-Tropsch is the basis for most GTL (Gas to Liquids) and CTL (Coal to Liquids) technologies.