State or mixture sensor. The mixture sensor comprises a sensor element having an element body which is made of a solid electrolyte having oxygen-ion conduction and which is coated on its opposite sides with electrodes, at least a portion of one of the electrodes being coated with a porous coating or deposit. The mixture sensor has a hollow outer holder having, at its end, an inwardly directed stepped shoulder on which the sensor element is mounted, the planes of the electrodes intersecting the longitudinal axis of the outer holder. The mixture sensor has a hollow cylindrical inner holder which is inserted into the outer holder and presses the sensor element against the shoulder of the outer holder and thereby secures it. It also has a connecting device which connects the interior of the inner holder to the exterior of the outer holder and terminal leads which are connected to the electrodes and serve to collect the signals from the electrodes.
