NOVELTY - The cell useful in a fuel cell and a reversible electrolyzer system for the electrolysis of water, comprises a planar cationic exchange polymer membrane (1), two electrodes (2, 3) placed one another in the membrane, a first catalyst (5a) for the reduction of protons in molecular hydrogen placed between the membrane and a cathode, and a second catalyst (5b) between the membrane and the anode. The first catalyst comprises a compound containing a family of heteropolyacid, which is stable in aqueous medium, family of metal-oxime, which is stable in aqueous medium and platinum nanoparticles.    USE - The cell is useful in a fuel cell and a reversible electrolyzer system for the electrolysis of water (all claimed) for the production of hydrogen and oxygen.    ADVANTAGE - The cell has high energy efficiency, electro-catalytic activity, chemical stability and electronic conductivity, and ensures economic electrolysis of water without using any noble metals thus capable of producing hydrogen and oxygen with high yield.    DETAILED DESCRIPTION - The cell useful in a fuel cell and a reversible electrolyzer system for the electrolysis of water, comprises a planar cationic exchange polymer membrane (1), two electrodes (2, 3) placed one another in the membrane, a first catalyst (5a) for the reduction of protons in molecular hydrogen placed between the membrane and a cathode, and a second catalyst (5b) between the membrane and the anode. The first catalyst comprises a compound containing a family of heteropolyacid, which is stable in aqueous medium, family of metal-oxime, which is stable in aqueous medium and platinum nanoparticles. The first and/or second catalyst is directly disposed on a surface of current collector, and absorbed to a specific surface of a material that is disposed between the membrane and the current collector. The material with the specific surface has carbon powder or carbon nanotubes, titanium oxide nanoparticles under stoichiometry, and tin oxide nanoparticles. An INDEPENDENT CLAIM is included for a process for the preparation of a cell for the electrolysis of water.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of cell for the electrolysis of water.    Cationic exchange polymer membrane (1)    Electrodes (2, 3)    Continuous current source (4)    First catalyst (5a)    Second catalyst. (5b)