Abstract: The processing of PFAS to convert them into safer substances comprises introducing gaseous or vapour phase PFAS into a treatment zone where microwave radiation of predetermined frequency and power level creates a plasma which at least partially dissociates the PFAS. There is also a system for remediating particulate solids, particularly soil, contaminated with PFAS, the method including directing microwave radiation to a body of particulate solids in the closed vessel so as to promote vaporization of PFAS which are then treated by exposure to the microwave produced plasma. Continuous and batch processing apparatus are disclosed. A preheating stage can dry the particulate solids to a pre-determined moisture content, and then a higher energy microwave heating promotes vaporization of PFAS. A partial vacuum created where particulate solids heated by the microwave radiation are yielding up PFAS promotes the vaporization of PFAS.