We are reporting here a potentiometric sensor by using yttria-stabilized zirconia (YSZ) as a solid electrolyte as well as zirconium silicate (ZrSiO4) added with Au as a sensing electrode (SE), for achieving sensitive and selective detection of hydrogen (H-2). The addition of 10 wt.% Au into ZrSiO4-SE increased the sensitivity toward 100 ppm H-2 at 500 degrees C, while lower responses to other examined gases were observed. The ability to detect H-2 selectively was elucidated via polarization-curve measurements in air and in N-2 and confirmed via gas conversion test. It was found that the sensitive and selective H-2 behavior was due to a lower catalytic activity against the gas-phase oxidation of H-2 than that of C3H6, in combination with a higher catalytic activity to anodic reaction of H-2 than that of C3H6. The good agreement between the observed sensitivity and the estimated value from the polarization-curve measurements confirmed that the sensing mechanism is based on mixed potential model. The sensor using ZrSiO4(+ 10 wt.% Au)-SE demonstrated a linear relationship between sensitivity and H-2 concentration on a logarithmic scale and was capable of detecting H-2 concentration as low as 20 ppm at 500 degrees C under humid conditions. (C) 2015 Elsevier Ltd. All rights reserved.