This paper proposes a way to investigate the benefit of hybridising a fuel cell vehicle with a second energy source such as batteries or supercapacitors packs. A global optimisation algorithm based on optimal control theory is proposed to determine an efficient power splitting between the fuel cell system (FCS) and the energy storage system (ESS). Both hybridisation and control strategy should minimise the hydrogen consumption for a given driving cycle. This method has fast computation time, and as a consequence many simulations can be performed within a short period, thus providing an interesting tool to test and compare different degree of hybridisation for various fuel cell hybrid vehicle (FCHV) parameters and driving cycles.