The ability of polymer electrolyte fuel cells (PEFCs) to startup at subfreezing temperatures is governed by whether it is able to overcome the freezing point (0 degrees C) before product ice prevents the electrochemical reactions. In this work, we experimentally investigated the coulombs of charge Q(c) transferred in PEFCs under subfreezing operation before the output voltage drops to 0.0 V. PEFCs with various membranes and catalyst-layer thicknesses, ionomer-carbon ratios, operating current density, and initial hydration of PEFCs were studied, and their influences on cold-start performance and coulombs of charge were experimentally measured. We find that subfreezing temperature, ionomer-catalyst ratio, and catalyst-layer thickness, significantly affect the amount of charge transferred before operational failure, whereas the membrane thickness and initial hydration level have limited effect for the considered cases. (C) 2013 The Electrochemical Society. All rights reserved.