The present disclosure relates to a sensor element for a potentiometric sensor, comprising a substrate formed from a metal alloy and an ion-selective enamel layer arranged on the substrate, wherein the metal alloy comprises at least one transition metal and wherein the ion-selective enamel layer contains a proportion of an oxide of the transition metal, and wherein an electrically conductive transition zone is arranged between the substrate and the enamel layer and contains the transition metal in a plurality of different oxidation states.