In this chapter, we consider the possibility of using hydrogen as a new fuel source to power an existing light aircraft. We compare the storage of hydrogen using high-pressure tanks with cryogenic tanks, favoring the latter due to weight considerations. We opt for using a fuel cell stack to liberate the energy stored in the hydrogen as electricity to drive the propeller via an axial flux, permanent magnet, synchronous electric motor to eradicate emissions of oxides of nitrogen, rather than use an internal combustion engine. We briefly consider the packaging of these items within the constraints of a typical light aircraft. We later outline the operation of the fuel cell stack showing that the operating points for maximum power and maximum efficiency differ. We discuss the role of the boost converter in matching the electric motor with the fuel cell stack.