Abstract: The invention is directed to a measuring cell for electrochemically detecting a gas sample and has at least one measuring electrode and one counter electrode disposed in a housing defining a chamber filled with an electrolyte. The measuring cell also includes a protective disc which is at least partially permeable and is improved so that the configuration of the measuring cell is substantially simpler and is of reduced volume without reducing the ion mobility in the electrolyte and with a significant supply of the electrolyte. The counter electrode is in the form of a layer and is applied to a region of the protective disc facing toward the electrolyte. this region is impermeable to the gas sample and the electrolyte. The counter electrode is further electrically insulated from the measuring electrode and is in permanent contact with the electrolyte. Only the measuring electrode and the diffusion membrane are applied to a region of the protective disc which is permeable to the gas sample.