Various porous flow fields have been proposed and developed for the cathode configuration of proton exchange membrane fuel cells to replace conventional channel-land flow fields. This study demonstrates the physical properties of porous metallic flow field and gas diffusion layers and quantifies the respective resistances during the oxygen reduction reaction in proton exchange membrane fuel cells with four different cathode configurations using electrochemical impedance spectroscopy and a theoretical model. The contribution of the flow field and gas diffusion layer to the oxygen reduction reaction is discussed, along with the relationship between the physical properties of these structures and water transport in the proton exchange membrane fuel cell.