A contact device of a new type - a sulfonic cation resin membrane (Nafio type) contact device for separating isotopes of hydrogen in the water-hydrogen system is represented. Its main feature is space separation of hydrogen and liquid water flows that allows using non-hydrophobic catalysts for realizing the process. Results of research on the isotope exchange efficiency carried out for model protium-deuterium system have been represented. Mass exchange efficiency dependencies on temperature (T = 333-413 K), pressure (P = 0.1-0.4 MPa), the hydrogen flow rate (GH2 = 20-120 NL/h) have been investigated for both hydrophobic and hydrophilic catalysts. High efficiency of membrane contact devices is noted in carrying out the chemical isotope exchange between hydrogen and water in the given range of conditions.