Method of remediating a soil contaminated by polyhalogenated hydrocarbons, in particular PCBs, PCDDs and PCDFs, comprising the steps of removing and sieving the soil to free it of stones and gravel; possibly regulating the moisture content of the sieved soil to a value of 10-30%; subjecting the sieved soil to thermal treatment while it flows in the form of a thin, turbulent, dynamic layer in contact with a wall heated to at least 250.degree. C.; separating the thermally treated soil from the steam generated following such treatment, the soil being substantially free of the aforementioned polyhalogenated hydrocarbons.