FIELD: chemistry.SUBSTANCE: group of inventions relates to biochemistry. An device and a method of producing methane (versions) is offered. The device includes a cathode reaction vessel to place carbon dioxide and aqueous electrolyte, an anode reaction vessel to place aqueous electrolyte, and also connection means for flow of direct current between the vessels. The cathode in the corresponding vessel is the base of methanogens of anaerobic Archaea. Cathode and anode reaction vessels are adapted to create a pressure of from 5 to 1000 bar in them. In one version, the method comprises passing direct current through anode and cathode, ensuring the ionization of hydrogen in the cathode reaction vessel, increasing the pH value of the aqueous electrolytic growing substrate, and forming oxygen out from the ionized oxygen in the anode reaction vessel. In another version, the method comprises feeding of aqueous growing substrate with methanogens of anaerobic Archaea into the reaction vessel, which is subjected to a pre
