Methods for synthesizing and identifying water-soluble fullerenes (fullerenols) were developed. When used as additives to corrosive media, fullerenes exhibit weak catalytic activity towards electrochemical corrosion of aluminum and steel. On the contrary, after the treatment of aluminum and steel with aqueous solution of fullerenols, the rate of electrochemical corrosion (in 0.25 N solution of sulfuric acid) increases by a factor of almost ten. At the same time, the specific surface electric conductance of aluminum and steel decreases by ten orders of magnitude. Thus, the metallic surface acquires insulating properties.