Hydrogen technologies are among the most promising low-carbon energies, and it fits perfectly the context of ecological transition. Carbon-free hydrogen represents a greener and more sustainable alternative to the batteries currently used for energy storage. There is a huge interest in optimizing the procedure for hydrogen production, use, and storage. This subject represents a particular interest for the CEA, EDF, and ORANO through several projects such as PEPR-H2 and udd@Orano. However, only a few works are carried out within the safety improvement framework of this energy production, transport, and use structures of this energy. Hydrogen leaks can represent a very high risk of a serious accident. In this project, we bring together several CEA departments expertise to develop a new hydrogen leak detection technology that can meet these major challenges. The combination of a simple chemical reaction (exothermic reaction) with distributed fiber optic sensors allows the creation of a new generation of hybrid sensors. These sensors use a reagent that heats up in the presence of hydrogen, leading to a temperature rise, which can be detected easily using an optical fiber distributed sensor. This measurement is characterized by high precision (can measure temperature variations of about 0.5 °C) with spatial resolutions that can reach the millimeter. These sensors will allow the monitoring of production lines, transport circuits, storage containers, etc., and provide real-time information on any containment system failure. Which will allow the localization of leaks with greater precision than the existing sensors. The low energy input (a few mW) and the absence of electronics reduce the risk of sparking, which makes the sensor functional and safe, even in the presence of high concentrations of hydrogen.