Durability performance such as sintering and voltage drops of HT-PEMFC was theoretically evaluated under non-humid conditions at 150 degrees C, 170 degrees C and 190 degrees C. The quantum chemical molecular dynamics showed that the affinity of the platinum (Pt) electxocatalysts with carbon support decreased with increasing temperature. The degree of agglomeration of electrocatalysts over time simulated by three-dimensional kinetic Monte Carlo method was compared and quantitatively agreed with experimentally measured Transmission Electron Microscopy (TEM) results. Agglomeration of electrocatalysts due to the sintering caused losses of electrochemically active surface area, and found to be occurred more severe as temperature increased. Decreased rate of the proton conductivity due to the evaporation of phosphoric acid affected voltage drops as temperature increased. A theoretical breakdown of the voltage drops indicated that the voltage drops that occurred during the first several hundreds of hours and those occurring for the latter stage were due to different effects. Copyright (c) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.