Accelerated stress test (AST) protocol meant to study the durability of catalyst support in a polymer electrolyte membrane fuel cell (PEMFC) electrode has been critically evaluated. For nanoparticulate catalysts supported on high surface area conductive materials (e.g. Pt/C), potential cycling meant to study the support durability causes significant impact on the catalyst particles presumed to be passivated due to formation of oxide layer. X-ray diffraction (XRD) patterns of pre-AST and post-AST samples suggest significant change in crystallite size during potential cycling between 1.0 and 1.6 V (vs. RHE), which may be considered to growth induced by dissolution/redeposition rather than particle growth through agglomeration due to support corrosion. Significant (similar to 50%) electrochemical surface area loss due to catalyst particle growth during support corrosion AST should be taken into account while development/screening of durable catalyst supports. To reduce such contribution, frequent observation cycle should be minimized.