NOVELTY - The electrochemical reactor comprises a galvanic cell, which has a metal anode (10) and an inert cathode (9) for operation of the galvanic cell and an aqueous solution as an electrolyte, and a fuel cell (2) operated with hydrogen, where the galvanic cell has openings for supplying and discharging the aqueous solution during the operation of the galvanic cell. The galvanic cell is designed as a hydrogen production cell (1). The reactor comprises a gas pipeline connecting the galvanic cell with the fuel cell for bringing the hydrogen produced at the cathode of the galvanic cell.    USE - Electrochemical reactor useful for power supply of a system, which is an electrically driven boat, a buoy, a sea-water mark, marine research plant, a board power supply system or an emergency power supply system (claimed).    ADVANTAGE - The electrochemical reactor can be simply, safely and economically produced in an environmentally friendly manner.    DETAILED DESCRIPTION - The electrochemical reactor comprises a galvanic cell, which has a metal anode (10) and an inert cathode (9) for operation of the galvanic cell and an aqueous solution as an electrolyte, and a fuel cell (2) operated with hydrogen, where the galvanic cell has openings for supplying and discharging the aqueous solution during the operation of the galvanic cell. The galvanic cell is designed as a hydrogen production cell (1). The reactor comprises a gas pipeline connecting the galvanic cell with the fuel cell for bringing the hydrogen produced at the cathode of the galvanic cell to the anode of the fuel cell. The hydrogen production cell is arranged in a reservoir containing the aqueous solution and partially below a surface of the aqueous solution, while the fuel cell is partially arranged above the surface of the aqueous solution. The fuel cell is arranged above the galvanic cell displayed as hydrogen production cell. The fuel cell comprises an inlet opening (14) to the supply of air oxygen to a cathode of the fuel cell and an outlet opening to the removal of produced water. The inlet opening and the outlet opening are arranged above the surface of the aqueous solution, while the openings of the hydrogen production cell are arranged below the surface of the aqueous solution. The reservoir is given through a sea or another water or a part of sea water or another water. The hydrogen production cell comprises an inlet valve, an outlet valve for closing the openings of the hydrogen production cell, and a pump for producing or maintaining a flow of the aqueous solution within the hydrogen production cell or through the hydrogen production cell. The hydrogen production cell comprises a housing containing an anode and a cathode of the hydrogen production cell, and a supply container arranged external of the housing and connected over the supply line with the housing, where the supply container has openings. The anode of the galvanic cell is formed from zinc or aluminum or magnesium or an alloy containing zinc and/or aluminum and/or magnesium as the hydrogen production cell. The hydrogen production cell and the fuel cell are electrically turned in row. A resistance load is connected or combined over the anode and the cathode of the hydrogen production cell to each other for increasing a fluent flow for the production of an excess of hydrogen or for balancing hydrogen losses through the hydrogen production cell. A filter is arranged in a progress or at an end of the gas pipeline and/or at an inlet opening leading to the cathode of the fuel cell. A memory is provided for a liquid oxidizer, which is guided from the memory of a cathode of the fuel cell. An INDEPENDENT CLAIM is included for a method of producing hydrogen.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of an electrochemical reactor.    Hydrogen production cell (1)    Fuel cell (2)    Inert cathode (9)    Metal anode (10)    Inlet opening. (14)