Abstract: The H₂-sensor was fabricated,based on AlGaN/GaN high electron mobility transistor(HEMT) device with a Pt-gate.The influence of the temperature and H₂-concentration on the response characteristics of the H₂-sensor,at a V_GS of -2.5 V,was investigated.The results show that the temperature and H₂-concentration had a major impact.To be specific,as the H₂-concentration increased from 25 to 900 ppm,depending linearly on the logarithm of H₂-concentration,the sensitivity increased by 14%;as the temperature increased from room temperature to 150℃,the sensitivity decreased,peaking at 25℃.The highest sensitivity of 65.9% was reached at 25℃ and 25 ppm.The temperature dependence of the sensitivity was theoretically modeled by modifying Langmuir adsorption isotherm and mathematically analyzed by data fitting.Possible mechanisms were also tentatively discussed in a thought provoking way.