Planar electrochemical sensors based on tape-cast yttria stabilized zirconia (YSZ, 8wt.% of Y 2 O 3 ) layers with two Pt parallel electrodes, one coated with WO 3 powders were prepared. The WO 3 powders were synthesized in the laboratory using different chemical routes. The NO 2 and CO potentiometric response of the sensors was measured at high temperature and compared to the response of the sensors fabricated using commercial WO 3 powders. Promising results in terms of selectivity, sensitivity, stability, reproducibility and response time were obtained for synthesized WO 3 -based sensors in comparison to the response of commercial WO 3 -based sensors.