Abstract: A method and system for liquifying natural gas using a cryogenic process is described. The method is well suited for producing high methane purity natural gas which can be used as a vehicle fuel. The invention utilizes residue gas from a cryogenic plant as a natural gas feedstock. The natural gas feedstock is condensed by heat exchange with overhead gas from the demethanizer of the cryogenic plant. In the preferred embodiment of the invention the pressure of the condensed natural gas is reduced to a level at which it can be readily stored and transported by expansion through one or more Joule-Thomson valves.