Air Cooled Polymer Electrolyte fuel cells (AC-PEFC) are recently receiving especial attention because they offer the possibility to integrate the oxidant and cooling subsystems in just one. This feature reduces not only the fuel cell weight, volume and cost but also the control complexity. In these fuel cells, the Oxidant/Cooling subsystem along with three others (Fuel, Electrical and Control) make up the Balance of Plant (BoP), which together with the stack comprise the full fuel cell. It is common to find works focused on analysing the influence of the Oxidant/Cooling subsystem on the fuel cell. Nevertheless, studies in which the Fuel subsystem (it is responsible for providing the hydrogen for its reduction oxidation reaction with oxygen to form water) is investigated are hard to find on the scientific literature. It seems like the Fuel subsystem configuration would not have influence over the whole system performance. Contrary to what one might think, and in basis on experimental results, this paper shows how the fuel cell performance is conditioned by the Fuel subsystem configuration. The aim of this paper is to present a comprehensive experimental study of an AC-PEFC paying particular attention, so unexplored so far, to Fuel subsystem configuration, giving the keys for the most suitable BoP configuration which guarantees the best performance, with the easiest BoP design and the lowest complexity. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.