A measuring sensor for determining gas compositions, includes a substrate consisting essentially of Al.sub.2 O.sub.3, electrodes disposed on the substrate, a sensor layer consisting essentially of TiO.sub.2 disposed above the electrodes, and an adhesion-improving layer which consists essentially of Al.sub.2 TiO.sub.5 and which is disposed on the substrate, the adhesion-improving layer being at least partially connected with the electrodes. The adhesion-improving layer is provided to improve the adhesiveness of the electrodes, and includes a material in common with the material of the sensor layer, i.e., Ti. The material of the adhesion-improving layer is selected so as to prevent a chemical reaction between the materials of the substrate and the sensor layer.