The Fuel_LF-RTO strategy is real-time optimization (RTO) strategy proposed here to find the optimal values of fueling for the polymer electrolyte membrane fuel cell hybrid power sources under unknown load profile, which is the case of fuel cell vehicle. The proposed optimization strategy is based on global extremum seeking (GES) algorithm and load-following (LF) control for air and fuel flows. The results show the performance obtained with Fuel_LF-RTO strategy in comparison with the Static Feed-Forward strategy. The performance was estimated for constant and variable load. The FC system efficiency and the fuel consumption efficiency for maximum load of 8 kW can increase with up to 1.88% and 11.26 W lpm(-1) in comparison with the sFF RTO strategy. Also, the fuel economy is 27.36 L during the 8 kW/12 s constant load cycle, which means an economy of 136.8 lpm. This performance is highlighted for constant load in range 2 to 8 kW, which represents 0.33% and 1.25% from nominal power of the 6 kW FC stack used in this study. Also, the performance was estimate for variable load considering the fuel economy, which can be up to 21.86 l during the 6.25 kW/12 s pulsed load cycle.