The anode and cathode starvation in proton exchange membrane fuel cells are studied using the electrochemical impedance spectroscopy. The impedances are measured while the anode and cathode feeding gasses are diluted using helium and nitrogen, respectively, and the Nyquist plots are compared against the normal operating conditions. It is shown that the cathode starvation significantly inflates the mid-frequency (MF) arc; while similar anode starvation does not affect the Nyquist plots of the measured impedances. These results are in agreement with the trends predicted from the process model presented. (C) 2016 Elsevier B.V. All rights reserved.