The JRC would like to procure a new gas detection system, consisting of oxygen and hydrogen detectors (approx. 12 oxygen detectors and approx. 4 hydrogen detectors, exact numbers depending on the technology used), and a central control unit, for its High-Pressure Gas Testing Facility (GASTEF) to replace an outdated one. The GASTEF facility is used for the experimental assessment of safety and performance of systems and components under pressurised hydrogen, and the gas detection system has a safety purpose for the facility. Some of the detectors will need to be able to operate in an inert atmosphere, i.e. nitrogen, and be compliant to ATEX zone 2 (Hydrogen) requirements. The procurement will need to include the supply of the gas detection system equipment, its installation and commissioning at the GASTEF facility, and preventive and corrective maintenances for a period of 8 years.