The effects of fuel processor faults in an solid oxide fuel cell (SOFC) system are analyzed. Focusing on a laboratory-size SOFC system, a reformer fault is investigated both experimentally and through a model; comparison between experimental and modeling results is presented and discussed. The results show that some types of reformer faults can be dangerous, because they can give rise to local thermal gradients as large as 10-20.10(2) K/m or more in the SOFC stack. Simulation results show that SOFC stacks employing metallic interconnects are expected to withstand faults of larger magnitude than SOFC stacks employing ceramic interconnects. Fault maps are presented and discussed, which can be the basis for the development of a fault detection and isolation (FDI) tool. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.