This paper reports on the computational performance and detailed results of ultra large-scale simulations of a 200 cm(2) polymer electrolyte fuel cell (PEFC) using a 23.5 million gridpoint mesh. The computer code is based on a comprehensive single-phase PEFC model that features a detailed membrane-electrode assembly (MEA) model, electron transport, thermal and species transport, coolant heat transfer, in addition to other standard functionalities. Two cases under dry operation are simulated and compared. One case concerns an infinitely large coolant flowrate and consequently a-constant temperature of bipolar plates. The other case involves a finite flowrate and a lower inlet coolant temperature designed to avoid membrane dryout in the inlet region while alleviating electrode flooding in the outlet region. (c) 2005 Elsevier B.V. All rights reserved.