NOVELTY - Preparation of a composite membrane comprises applying to a porous support having an average surface energy of 1-30 mN/m, a composition having a viscosity of 1-5000 mPa.s; and increasing the viscosity of the composition to higher than 30000 mPa.s within 30 seconds after the composition has been applied to the support. The applied composition has a surface tension that is greater than or equal to 25 mN/m higher than the average surface energy of the porous support.    USE - The process is for preparing a composite membrane used as ionically charged membrane for use in electrodeionization unit. The composite membrane is used in electrodialysis or reverse electrodialysis unit, flow through capacitor, fuel cell, diffusion dialysis apparatus, and membrane electrode assembly. It is used for the purification of water by removal of dissolved ions, wastewater treatment, electrolysis, pervaporation, generation of electricity, separation of gases and vapors (all claimed), filtration techniques (e.g. reverse osmosis and nano- and microfiltration), functional textiles e.g. technical or protective clothing, dehumidification, and Donnan or diffusion dialysis e.g. for fluoride removal or the recovery of acids. The composite membrane is used as anion or cation exchange membrane. The process is also used to make membranes without the composition permeating through the support and fouling surfaces, e.g. rollers, which may be used in an automated process. It is used to produce homogeneous membranes as well as heterogeneous membranes.    ADVANTAGE - The composite membrane has an ion exchange capacity of greater than or equal to 0.3 meq/g based on the dry weight of the membrane; and water permeability at 20 degrees C of lower than 1x 10-7 m3/m2.s.kPa. The ion exchange membranes with weakly basic or acidic groups can exhibit good properties in terms of their permselectivity and conductivity while at the same time being not overly expensive to manufacture. The manufacture of membranes is conducted in a simple process that may be run continuously for long periods to mass produce membranes relatively cheaply.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a composite membrane comprising a porous support having an average surface energy of 1-30 mN/m, as measured before coating; and a polymeric layer in contact with the porous support, having an average surface energy of greater than or equal to 30 mN/m and comprising cured ethylenically unsaturated compounds; and    (2) electrodeionization unit comprising ion-concentrating compartment, ion-depleting compartment, anode, cathode, and ionically charged membranes separating the compartments, where at least one of the membranes is obtained by a process of preparing a composite membrane.