Carbon blacks are widely used as electrocatalyst supports in polymer electrolyte fuel cells (PEFCs), and the corrosion of carbon blacks has a severe impact on the long-term durability of PEFCs. The steam etching approach was used to investigate the corrosion of the low-surface area XC72 carbon black and the high-surface area black pearl 2000 carbon black under different conditions. The weight loss of the XC72 and the black pearl 2000 when etched at 800 degrees C for 3 h is 28.43% and 54.82%, respectively. TEM results show that the corrosion of the XC72 begins from the center of the particle, while the corrosion on the black pearl 2000 starts on the particle surface. XRD results show that the 0 0 2 and 10 peaks of the XC72-based samples are initially sharp, but then broaden during the corrosion process. For black pearl 2000-based samples, the 0 0 2 and 10 peaks all became broader during the corrosion process. The results provide guidelines for modifying carbon black as catalyst supports to achieve a higher durability. (C) 2010 Elsevier B.V. All rights reserved.