Micro-thermoelectric hydrogen sensor (micro-THS) was fabricated to operate with its unique working principle of the combination of the thermoelectric effect of SiGe thin film and the Pt-catalyzed exothermic reaction of hydrogen oxidation. We focused on improving sensitivity and response speed of micro-THS using a new catalyst deposition method. Comparing with the two catalysts of thin and thick film technology, sensitivity of the micro-THS with Pt/alumina thick film catalyst was 5 times higher than that of the sensor with Pt thin film catalyst. The Delta TA- B of Pt/alumina thick film catalyst was large enough for a wide detection range of hydrogen concentration from 25 ppm to 3%, although its size was small, 35% of the Pt thin film one. At operating temperature of 100 S C, for the low hydrogen concentration of 25 ppm, clear response of 0.03 mV the micro-THS with Pt/alumina thick film catalyst was observed. (c) 2006 The Electrochemical Society.