A method of producing a sol of an element selected from the group consisting silicon, aluminum, antimony, chromium, manganese, molybdenum, tin and tungsten comprising electrodialytically transferring alkali metal cations of an aqueous solution of a water soluble alkali metal salt of the oxide of the said element from an anode compartment of an electrolytic cell to a cathode compartment of the electrolytic cell while essentially preventing the migration of the metal oxide into the cathode compartment by positioning a cation permselective membrane between the anode compartment and the cathode compartment while carefully and continuously controlling the pH of the solution and removing the so-produced sol from the anode compartment of the electrolytic cell as well as a novel electrodialytic cell for sol formation.