Method of manufacturing a device for detecting a gas or gas mixture, - wherein a semiconductor chip is produced, in that - a first semiconductor substrate is provided, - a first drain, a first source, a first channel region disposed therebetween and a first gas-sensitive layer, which contains palladium and which reacts by a change in its work function to a change in the concentration of the gas to be detected, are formed at the front side of the first semiconductor substrate, - wherein the first channel region and the first gas-sensitive layer are so arranged that the first gas-sensitive layer is capacitively coupled to the first channel region, and - the rear side of the first semiconductor substrate is coated with a second gas-sensitive layer which reacts by a change in its work function to a change in the concentration of the gas to be detected, - wherein a second semiconductor chip is produced, in that - a second semiconductor substrate is provided, - on which a second drain, a second source and a second channel region disposed therebetween are formed, wherein the first semiconductor chip and the second semiconductor chip are so positioned relative to one another that the second gas-sensitive layer faces the second channel region and is capacitively coupled thereto by way of an air gap and wherein the first semiconductor chip and the second semiconductor chip are fixed relative to one another in this position. - wherein a semiconductor chip is produced, in that - a first semiconductor substrate is provided, - a first drain, a first source, a first channel region disposed therebetween and a first gas-sensitive layer, which contains palladium and which reacts by a change in its work function to a change in the concentration of the gas to be detected, are formed at the front side of the first semiconductor substrate, - wherein the first channel region and the first gas-sensitive layer are so arranged that the first gas-sensitive layer is capacitively coupled to the first channel region, and - the rear side of the first semiconductor substrate is coated with a second gas-sensitive layer which reacts by a change in its work function to a change in the concentration of the gas to be detected, - a first semiconductor substrate is provided, - a first drain, a first source, a first channel region disposed therebetween and a first gas-sensitive layer, which contains palladium and which reacts by a change in its work function to a change in the concentration of the gas to be detected, are formed at the front side of the first semiconductor substrate, - wherein the first channel region and the first gas-sensitive layer are so arranged that the first gas-sensitive layer is capacitively coupled to the first channel region, and - the rear side of the first semiconductor substrate is coated with a second gas-sensitive layer which reacts by a change in its work function to a change in the concentration of the gas to be detected, - wherein a second semiconductor chip is produced, in that - a second semiconductor substrate is provided, - on which a second drain, a second source and a second channel region disposed therebetween are formed, - a second semiconductor substrate is provided, - on which a second drain, a second source and a second channel region disposed therebetween are formed,