Electrochem. treatment of soils to 2 clays, kaolinite and montmorillonite, polluted with Cu was studied. Montmorillonite has higher exchange properties than kaolinite, conducting to stronger interaction between this clay and Cu. Electromigration of Cu takes place from the anode towards the cathodic compartment where the Cu is collected. Soil nature and its exchange capacity is detg. the extn. rate of Cu. Extn. is quicker on kaolinite than on montmorillonite. For both soils, final extn. rate were >85% of the initial Cu amt. present in the soil. The control of operating pH conditions allows optimization of this process. The gradient pH through the soil influences its comportment and the chem. of the pollutant. Acidification of the soil, by migration of protons from anode to cathode, favors the exchange reaction between protons and Cu and by consequence the release of sorbed Cu in the liq. phase and its extn. The coeff. of useful charge describes the initial extn. slope of the pollutant. This parameter is specific to the clay and the pollutant but independent of the scale of the cell. [on SciFinder (R)]