This paper focuses on the cold start performance of proton exchange membrane fuel cell (PEMFC) in order to improve its capability and survivability. With the printed circuit board (PCB) technology, the change of internal current density and temperature under different operations would be obviously shown. The result shows that the initial voltage load and setup temperature is significant for the cold start ability. Polarization curves show almost no performance degradation after the successful cold start, but it degrades quickly after the failed cold start. The highest current density appears in the inlet region and then it reaches to the middle region of the cell, which accompanies with the thermal drifting. When the cell continues to work at normal condition, a decreasing tendency appears in the inlet and middle regions, but the performance of the outlet region is increasing. Based on these characteristics of performance, the method of delivering humidified H-2 and air to the PEMFC was adopted to optimize the uniformity of the current density distributions of the cell. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.