NOVELTY - The converter has a fuel cell (50) e.g. alkaline fuel cell, including an anode (51) separated from a cathode (52) by an electrolyte (53) for generating electric direct current from hydrogen and oxygen produced by another electrolyte (43). A gas supply unit supplies the anode and the cathode of the cell with the hydrogen and oxygen that are produced at a cathode (42) and an anode (41) of an electrolyzer (40), respectively. A water supply unit supplies water to the anode of the electrolyzer. Current collectors (61, 62) collect the electric direct current that is generated by the cell.    USE - Electric direct current-direct current converter for converting electric direct current to electric direct current to assure galvanic isolation between input and output electric circuits in a system requiring low current and high voltage such as micro-electro-mechanical system (MEMS), nano electromechanical system (NEMS) and electrowetting microfludics system.    ADVANTAGE - The converter converts direct input current to direct output current with high efficiency, while assuring galvanic isolation between the input and output electric circuits when the electrolyzer is not electrically contacted with the cell and fluidic communication is assured between the electrolyzer and the cell. The configuration of the converter ensures clean reactive gas supplied to the cell, and permits limitation of ohmic or magnetic loss related to different used electric units. The converter does not have separate porous substrate reservoir or a connection unit for connecting the cathode of the cell to the anode of the electrolyzer so as to reduce the number of pieces, thus simplifying the structure of the converter, and hence reducing the fabrication cost of the converter. The converter is configured such that the electrolyzer is arranged opposite to the cell, and a porous substrate has reduced thickness so as to reduce the path length of the hydrogen, thus reducing the response time of the converter.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for converting electric direct current to electric direct current.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic sectional view of an electric direct current-direct current converter.    Electrolyzer (40)    Anode of electrolyzer (41)    Cathode of electrolyzer (42)    Electrolytes (43, 53)    Fuel cell (50)    Anode of fuel cell (51)    Cathode of fuel cell (52)    Current collectors (61, 62)