Synthesis of Liquid Hydrocarbons from Synthesis gas which has been largely commerciallized for producing morter fuels from coal are described on their present status and future prospect. Carbon number distribution of product hydrocarbon from Fischer-Tropsch (F-T) synthesis on iron, cobalt and ruthenium catalysts have been shown to follow well the Schulz-Flory law which is derived from the assumption that the chain propagation probability is independent of carbon number. The probability of chain propagation is well controlled by regulating potassium content in the catalyst (for iron) or by regulating the size of metal particles (for ruthenium). Hydrocarbons from F-T synthesis are rich in normal paraffins and olefins while those from methanol conversion on zeolite are composed of iso-paraffins and aromatics. Slurry phase F-T process is suggested to be the most promising as the indirect coal liquefaction process for next generation. It is pointed out from the chemical structure of product hydrocarbon that F-T process is suitable for producing kerosene and diesel fuel whereas the direct coal hydrogenation is favored for producing gasoline base oil.