The development of the control of a Fuel Cell/Supercapacitor system for Electric Vehicle must take into account the stability constraints related to the associations of its components. Numerous studies have achieved control and energy management of Fuel Cell/Supercapacitor Electric Vehicle but real-time applications are insufficient or the stability is not ensured. In this paper, the development of a stable control of the Fuel Cell/Supercapacitor system is proposed by the backstepping method. The backstepping control design procedure is depending on different power paths and a physical decomposition prepares its design. Energetic Macroscopic Representation is used for this purpose. The vehicle power distribution is performed in simulation by the developed stable control and a proposed thermostat strategy.