An yttria-stabilized zirconia (YSZ)-based potentiometric sensor utilizing a powdered mixture of ZnO and Ta2O5 as a starting material for the sensing electrode (SE) was examined for sensitive and selective detection of H-2. After sintering at 1000 degrees C, an addition of 30 wt% Ta2O5 to ZnO was experimentally found to form a mixture of ZnO, Ta2Zn3O8 and TaO2. In this-case, the highest responses toward H-2 and hydrocarbons (HCs) were generated, when compared with other ZnO/Ta2O5-based SE materials. Improvement of the sensing characteristic was conducted by increasing sintering temperature from 1000 to 1300 degrees C. After sintering at 1300 degrees C for 2 h, the sensor using ZnO(+30 wt% Ta2O5)-SE showed a significant response toward H-2, with only minor sensitivity toward other gases such as NOx and HCs. The results from SEM observation and XRD measurements confirmed that an increase in the sintering temperature altered the morphology as well as the chemical composition of the SE, which are believed to change the catalytic properties of SE, leading to higher sensitivity and selectivity toward H-2. The obtained sensor exhibited a linear relationship between sensing signal and H-2 concentration, with a lower detection limit of 20 ppm. (C) 2013 The Electrochemical Society. All rights reserved.