Activated carbon composite support (ACCS) is synthesized using a novel methodology developed at University of South Carolina (USC). The ACCS shows good thermal stability similar to that of carbon nanofibers (CNFs). Pt/ACCS catalyst shows excellent support stability under simulated start-up/shut-down operating conditions (1.0-1.5 V, 5000 cycles). The Pt/ACCS shows a maximum power density of 722 mW cm(-2) while commercial Pt/C and Pt/290G catalysts show 495 and 530 mW cm(-2), respectively. Furthermore, Pt/ACCS shows no loss of mass activity and maximum power density after 5000 cycles at 1.0-1.5 V. The commercial Pt/C and Pt/290G catalysts show drastic mass activity losses (57.5% and 66.2%, respectively) and maximum power density losses (88.7% and 84.0%, respectively). The good activity and excellent stability of Pt/ACCS catalyst are attributed to the higher degree of graphitization and enhanced hydrophobicity of ACCS. For the first time, we report a carbon-based support which is stable under simulated start-up/shut-down operating conditions. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.