Hydrogen Fuel cells technology is a major contributor to the future developments of the automotive industry thanks to its CO2 reduction potential. Still, the vehicle design with such technology needs to overcome several challenges, especially from a safety standpoint. In the present work, the complete integration process of a hydrogen PEMFC range extender onboard an existing vehicle is examined, starting from the SIMULINK® model of the vehicle mission to have the basic target requirements accomplished. In the first chapter, the project background will be shortly presented. In fact, the system integration presented in this work is carried over an already existing vehicle, the “research” prototype Blizz Primatist.