We present here a model we have established for a laboratory-size SOFC system. Model equations are presented and discussed, together with an extensive model validation, carried out in both steady state and transient operating conditions. The validated model is then used to simulate four classes of system faults, i.e. air leakage, fuel leakage, SOFC degradation and reformer degradation. When the different faults occur, the physico-chemical operating parameters of the system vary in a different manner, and our main objective is to understand their behavior. For example, for the system under analysis, SOFC degradation and fuel leakage cause a decrease of the gas discharge temperature, while reformer degradation causes an increase of the same parameter. The results of the fault analysis are described and discussed, and are reported in such a way to provide a basis for the development of an FDI tool based on pattern recognition techniques. (C) 2014 Elsevier Ltd. All rights reserved.