This work discusses the origins and development of SFC, the instrumentation that has been used and the technique's growth from the related methodologies of GLC and HPLC. It also covers in more detail the ways in which the separation in SFC can be altered to increase selectivity, compares the roles of packed and capillary columns and covers the coupling of SFC to mass spectrometry. SFC is a rapidly expanding analytical technique which will have great impact on analytical procedures in the petroleum, pharmaceutical, food, agrochemical and biotechnology industries. The RSC Chromatography Monographs series aims to cover all aspects, techniques and applications and will include GLC, HPLC, TLC, SFC, affinity chromatography and counter-current chromatography. It is intended for use by the individual practising chromatography on a day-to-day basis in the laboratory.