The use of fuel cell hybrid vehicles is a potential transport solution achieving zero emission once technical, economic, and social challenges are overcome. Energy management strategies on board remain an important research subject in a quest to find an efficient power splitting between the fuel cell system and the energy storage element of the hybrid powertrain. This paper proposes an online strategy based on a fuzzy decision system. Fine tuning of the fuzzy system parameters, mainly the membership functions, is made possible using a powerful optimisation tool which is a genetic algorithm. This optimisation procedure takes into consideration the minimisation of the hydrogen consumption while satisfying the requested power over a given driving cycle.