Abstract: In an electrochemical cell arrangement for the deionization of aqueous solutions by ion exchange including cathode and anode chambers having electrodes disposed therein, a brine chamber is disposed between, and directly adjacent to, the cathode and anode chambers which are filled with anion and cation exchanger materials such that the electrodes are directly in contact therewith and means are provided for conducting the aqueous solution to be treated through the cathode and anode chambers and means for passing brine through the brine chamber to be charged therein by the ions removed from the aqueous solution in the cathode and anode chambers.