The invention relates to an electrode assembly for the electrochemical treatment of liquids with a low conductivity. Said assembly comprises electrodes (1, 2), between which a polymer solid electrolyte (3) is situated. The electrodes are pressed against one another by means of a compression device (9, 10; 91) and are configured in such a way that the assembly can be traversed by the liquid To produce said assembly simply and to ensure that it is flexible and easy to use, the compression device (9, 10; 91) is supported on the electrodes (1, 2).