Today, global warming has reached alarming levels and will only worsen if greenhouse gas emissions are not reduced. Of all types of transport, aviation is the most polluting. A solution for decarbonizing the aerospace industry is represented by hydrogen, thanks to its high gravimetric energy density. However, the main challenge of H2 is related to its storage. Due to its very low density, H2 is not competitive in the transport sector. Thus, to increase its density, technologies such as compressed hydrogen, liquified hydrogen, liquid organic hydrogen carriers and metal hydrides are used. The fuel cell system is another key component in the decarbonization scenarios.