The cell degradation in high-temperature proton exchange membrane fuel cells (HT-PEMFCs) using phosphoric acid (PA)-doped polybenzimidazole (PBI) membranes is one of the most important challenges to be improved for its early commercialization since the reported lifetime of the HT-PEM is too deficient to meet the commercially required target. The aim of this paper is to numerically investigate the effects of operating conditions on the performance degradation of HT-PEMFC. In order to resolve this problem, a one-dimensional model for the HT-PEM with PA-doped PBI membrane has been developed based on the hybrid modeling method and the model validated with HT-PEMFC polarization curves obtained by ourselves. Using the developed model, activation and ohmic overpotentials at each layer could be analyzed through membrane electrode assembly (MEA). The simulation results demonstrate that the durability of HT-PEMFC is changeable with respect to current density and PA doping level. In addition, the lifetimes have been predicted according to different operating conditions and thus we found whether any conditions are helpful to improve lifetime of HT-PEM or not. (C) 2013 Elsevier B.V. All rights reserved.