The main methods of treatment of natural adsorbents: thermal, electrochemical and hydrothermal ones and their activation by means of acids, bases and organic compounds have been briefly reviewed. Some changes in physico-chemical and electro surface properties of Moldavian benthonite and diatomite under electrotreatment conditions are considered. Adsorption-structural characteristics of adsorbents after their treatment in cathodic and anodic cells and in diaphragmless electrolytic cell are compared. A significant role of the electrolytic gases in adsorbents particles dispergation has been pointed out as well as the effect of soluble products of electrolysis (carbonic acid, protons and hydroxyl ions) on increasing of active groups on the adsorbent surface which is followed by growth of negative charge density of the particles. The electro treated samples of benthonite and diatomite are shown to possess much more capacity against selenium and fluorine ions in comparison with untreated ones.