The printed circuit board (PCB) technique is one of the In-situ segmented cell measuring techniques which can provide real-time, accurate current density distributions and reflect the uniformity of the internal electrochemical reaction in the fuel cell. The PCB technique and electrochemical impedance spectroscopy (EIS) were utilized to study the effects of operating temperature on the current density distributions and membrane resistances. The operating temperatures were respectively chosen at 50, 70 and 90 degrees C, operated at the load of 10 A, to observe the polarization curves, the internal segmented current density distributions and membrane resistances. The polarization curves showed that at 70 degrees C, the performance of fuel cell was the best and the current density distribution was evenly distributed. The results of EIS also demonstrated that at 70 degrees C, the resistance of fuel cell was the lowest. The effects of different loads on the current density distribution at 70 degrees C were also studied. It showed that with increasing loads, the current density distributions became more and more unevenly. This was mainly because the increasing of loads would produce more water at the exit, which led to the hinder of the air circulation, and then it induced to the increase of inhomogeneity of the current density distributions. Crown Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.