Abstract: Device for determining the Wobbe index of a first gas mixture, including a Wobbe index meter having a mixing chamber, and a feed system for supplying a first gas mixture and an oxidation gas to the mixing chamber of the Wobbe index meter. The feed system includes structure for supplying the first gas mixture to the mixing chamber via a first number of openings, structure for supplying an oxidation gas to the mixing chamber via a second number of openings, structure for keeping a constant ratio between the a quantity of first gas mixture and the a quantity of oxidation gas supplied to the mixing chamber, structure for burning the second gas mixture formed in the mixing chamber and structure for determining the oxygen content of the combustion gas obtained after combustion.