Sulphur hexafluoride (SF₆) is an excellent dielectric gas for high voltage applications. It is chemically inert, gaseous even at low temperature, non flammable, non toxic, non corrosive. Its combined chemical, thermal and electrical properties allow many advantages to be achieved.

SF₆ allows simplified design of high and medium voltage switchgears because of size and weight reduction, quiet and reliable handling and maintenance. Outstanding properties are its dielectric strength and dielectric constant unchanged from a few Hz up to several GHz, and such as arc quenching properties to prevent arc from occurring while its molecular fragments rapidly recombine after the source of arc is removed. Furthermore the high molar heat capacity and low viscosity enables it to transfer heat very effectively.