This study investigated a method for characterizing the behaviour of clays in an aqueous medium in the presence of an electric field. The experiments were performed with different clays (kaolinite, smectite, kaolinite-smectite) suspended in deionized water. An apparatus was developed for measuring a continuous electric current under the singular effect of adding sodium silicate to the aqueous suspensions. The results showed that the method allows the differentiation of the investigated clays through their electrophoretic behaviour in an aqueous solution.