Method of treating unburnt methane by oxidation by plasma

A method of treating a methane residue in a gas mixture, said method comprising a step of introducing said gas mixture into a plasma reactor and a step of generating a plasma in the plasma reactor, wherein:

• the gas mixture introduced into the plasma reactor has a temperature lying in the range 200° C. to 500° C. and includes at least methane at a concentration in the range 50 ppm to 2500 ppm and oxygen at a concentration lying in the range 0.5% to 12% by volume;
• and
• wherein a plasma having energy density lying in the range 15 J/L to 100 J/L is generated during the plasma generation step by applying a high voltage electrical signal between an internal electrode and an external electrode of said plasma reactor, said external electrode being cylindrical in shape and surrounding the internal electrode, and at least one of said electrodes being covered in a dielectric material for creating a dielectric barrier discharge in the gas mixture and converting part of the methane residue into carbon monoxide.