In order to ensure the safety of hydrogen energy system, a robust and reliable hydrogen sensor device with an optical fiber Bragg grating (FBG) has been developed. The sensing mechanism is based on temperature changes in the device induced by the heat of the catalytic reaction of hydrogen on platinum-loaded fumed silica catalyst powder. Through optimization of the preparation conditions for the catalyst, which is a hydrogen-sensitive substance, a large degree of heat generation in the presence of hydrogen could be obtained, and good stability was also achieved. A sensor device in which a column filled with the obtained catalyst powder was attached to a commercially available robust FBG for tem-perature measurement, and integrated with another FBG as a temperature reference via a heat shielding plate, was fabricated and evaluated. A stable baseline was demonstrated even in an environment where the ambient temperature severely fluctuated, and a sensor output proportional to the hydrogen concentration could be obtained. The detection limit was about 0.2 vol%, and the long-term stability of the device was good.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.