The HYDEA project, which stands for “HYdrogen DEmonstrator for Aviation”, proposes a robust technology maturation plan to develop an H2C (Hydrogen Combustion) propulsion system compatible with an Entry Into Service of a zero-CO2 low-emission aircraft in 2035, consistently with the expected timeframe of the European Green Deal and CA SRIA objectives. The project aims to address fundamental questions related to the use of hydrogen as an aviation fuel, concentrating on the development and testing in relevant conditions of an H2 combustor and H2 fuel system, also including emission studies and further technologies which will serve as an outlook to future engines, i.e. NOx optimization studies, potential contrails emissions and investigating integration aspects between engine and aircraft. HYDEA results will be core for the ZEROe technology exploration project, launched by Airbus in 2020. The revolutionary technologies in scope call for an early engagement and dialogue with EASA (European Union Aviation Safety Agency) within HYDEA, starting from phase 1.