Improved durability and reduced precious-metal loading are objectives of current polymer-electrolyte fuel-cell research. One path toward these objectives that shows promise is the use of ultrathin catalyst layers, which have thicknesses of less than 0.5 mu m. In contrast, conventional platinum-on-carbon porous electrodes are generally between 10 and 20 mu m thick. A disadvantage of ultrathin cathodes is their tendency to flood at low temperature, which could increase the time required to start the cell after an extended shutdown. In the present work, the cold-start performance of a polymer-electrolyte fuel cell with an ultrathin cathode is investigated by modifying a cold-start model (presented previously) such that the cathode is taken to be an infinitesimally thin surface. Performance is predicted over a temperature range of -40 to -5 degrees C. Comparisons are made to an equivalent conventional cell, parametric studies are performed, and mitigation strategies are investigated. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3607968] All rights reserved.