Abstract: A process for producing a liquefied natural product such as LNG is described where a single phase nitrogen refrigerant is used in such a way that the refrigerant stream (10) is divided into at least two separate portions (12, 14) which are passed through separate turbo-expanders (106, 108) before being admitted to separate heat exchangers (103, 104) so that the warming curve of the refrigerant more closely matches the cooling curve of the product being liquefied so as to minimize thermodynamic inefficiencies and hence power requirements involved in operation of the method.