In this paper, two main groups of technologies and applications that can be distinguished regarding hydrogen field: gas production (hydrogen and oxygen), and power generation, are presented. Firstly, for gases generation, reforming of bioethanol and PEM electrolysis are presented as possible choices for hydrogen production for terrestrial plants related to space activities. In the case of on board gases production, electrolysis is presented as the most suitable option. Secondly, regarding power generation with fuel cells, different applications are presented (landers, aircrafts, stationary back-ups, APUs, UAVs, etc.). Thirdly, two options of combination of power generation with fuel cells and gases production are shown: reversible fuel cell systems and regenerative fuel cell systems, and a comparison between the current batteries used and these regenerative fuel cell systems. In the conclusion, two applications scales are presented: one for power generation depending of the level of power generated, and another one for gases generation depending of the gases production rate.