Persulfate is another commonly used oxidizing agent for in-situ chemical oxidation applications. It is most frequently applied in the subsurface as sodium persulfate (NaS₂O₈). The reaction that occurs produces a strong oxidizer (the persulfate radical). Below are the basic reactions to obtain the persulfate radical. In addition, the reduction potentials for several other oxidants used for ISCO are listed. The persulfate radical is a stronger oxidizer than hydrogen peroxide, permanganate, and ozone. Only the hydroxyl free radical is a stronger oxidizer.

Persulfate radicals are most readily formed with the addition of heat or the use of a transition metal catalyst:

Sodium persulfate is effective against a wide range of contaminants, including:
Hydrocarbons
	BTEX		MTBE
	Ketones		PAH
	Dioxane
Chlorinated Solvents
	Dioxane		PCE
	TCE		DCE
	VC		CB
	DCA		CH2Cl2
	CHCI		PCB
	Chloromethane
Pesticides

Persulfate Limitations
	Creates high sulfate conditions in groundwater
	Not well tested in-situ
	Difficult to control / catalyze
	Requires elevated temperatures to remediate contaminants