A method for the decontamination of a soil, sediment, or sludge containing toxic halogenated organic compound and containing water comprising the steps of mixing said soil, sediment, or sludge with a reagent capable of reacting with said halogenated compound and heating said mixture of soil, sediment, or sludge, and reagent in a reaction zone to an elevated temperature thereby forming a reaction zone vapor stream containing at least a portion of the water contained in said soil, sediment, or sludge and unreacted halogenated organic compound; condensing a portion of said reaction zone vapor stream under conditions suitable for the formation of a condensate stream containing substantially all of the halogenated organic compound in said reaction zone vapor stream, and a vapor stream containing water and trace amounts of said halogenated organic compound; recycling said condensate to said reaction zone; treating said vapor stream to remove trace halogenated organic compound and venting the so-treated stream to the atmosphere; and removing soil, sediment, or sludge containing less contaminant from said reaction zone.