Different break-in procedures for phosphoric acid doped polybenzimidazole membrane fuel cells (PBI-FC) have been studied, including voltage cycling and the use of constant current at different temperatures. A rapid break-in procedure consisting of high-temperature constant current break-in and relaxation has been developed. The break-in procedure is considered suitable for contamination and performance studies. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved