NOVELTY - The procedure and/or device for simultaneous production of a gas product (8, 20) and/or a product out of element (4) existing out of hydrogen, carbon monoxide and methane pre-existed to predominant part of fluid methane (10), comprises carrying out a cryogenic gas splitting (C) in fractions through a cryogenic gas splitter by the separation of insert in an arrangement. The product purity having methane fraction is drawn-off fluidly from the cryogenic gas splitting and after under cooling, when the fluid methane is temporarily stored in a tank (T).    USE - Procedure and/or device for simultaneous production of a gas product and/or a product out of element existing out of hydrogen, carbon monoxide and methane pre-existed to predominant part of fluid methane.    ADVANTAGE - The procedure ensures effective and simultaneous production of gas product and/or product out of element existing out of hydrogen, carbon monoxide and methane pre-existed to predominant part of fluid methane with good quality, high yield and less energy consumption.    DETAILED DESCRIPTION - The procedure and/or device for simultaneous production of a gas product (8, 20) and/or a product out of element (4) existing out of hydrogen, carbon monoxide and methane pre-existed to predominant part of fluid methane (10), comprises carrying out a cryogenic gas splitting (C) in fractions through a cryogenic gas splitter by the separation of insert in an arrangement. The product purity having methane fraction is drawn-off fluidly from the cryogenic gas splitting and after under cooling, when the fluid methane is temporarily stored in a tank (T). The cryogenic splitting is carried out by gas washing with fluid carbon monoxide (T1) through a wash column, and by separating carbon monoxide/methane (CO/CH4) in a CO/CH4 separation column. The fluid methane fraction having product purity is drawn-off from the sump of the CO/CH4 separation column. The cold use of the cryogenic gas splitting is covered through a 2-stage expansion turbine/compressor process or through a mixed cold circulation in which a cooling agent existing out of two components is supplied. Nitrogen and/or carbon monoxide is used as circulation medium. The component of the cooling agent is nitrogen, methane, ethene, ethane, propane, propene, butane and/or pentane. The separation column has a reboiler, over which the separation column is heatable. The energy is withdrawn for heating the separation column. The element for cryogenic gas splitting has a methane content of 10 mol.%. The methanol synthesis gas (2), oxogas and/or carbon monoxide are produced as gas products. The element is decomposable in the cryogenic gas splitter. A circulation flow existing out of nitrogen and/or carbon monoxide is releasable over an expansion turbine, which is coupled with a compressor for covering the cold use of the cryogenic gas splitting. The compressor condenses a part of circulation flow. In the cryogenic gas splitter, a cooling agent (80) existing out of two components is introducible in a cooling circuit.    DESCRIPTION OF DRAWING(S) - The figure shows a synthesis gas plant for the production of methanol synthesis gas, carbon monoxide and fluid methane.    Synthesis gas (2)    Element (4)    Gas product (8, 20)    Fluid methane (10)    Cooling agent. (80)