Research on nanostructured fuel cell electrodes has recently been growing significantly. Although improvements on the charge capacity and lifetime of nanostructured electrodes have been frequently reported, an analytical evaluation of the energy loss of nanostructured fuel cells is still lacking. In this communication, an electrochemical cell is designed and analyzed to measure the gas diffusivities through electrodes. With the measured gas diffusivities, the correlation between the concentration polarization energy loss and the important parameters associated with nanoscale electrodes in gas–fuel based fuel cells, such as temperature, and the porosity of the electrodes, can be efficiently analyzed.