Method of cooling a hydrocarbon stream (10) such as natural gas, the method at least comprising the steps of (a) heat exchanging the hydrocarbon stream (10) against a first refrigerant stream (20) to provide a cooled hydrocarbon stream (30) and an at least partly evaporated refrigerant stream (40); (b) compressing the at least partly evaporated refrigerant stream (40) using one or more compressors (14, 16, 18) to provide a compressed refrigerant stream (50, 60, 70); (c) cooling the compressed refrigerant stream (50, 60, 70) after one or more of the compressors against ambient to provide a cooled compressed refrigerant stream (70a); (d) dynamically expanding the cooled compressed gaseous refrigerant stream (70a) to provide an expanded refrigerant stream (80); and (e) further cooling the expanded refrigerant stream (80) to provide an at least partially condensed refrigerant stream.