Both high temperature (HT) and intermediate temperature (IT) SOFC performances are evaluated using numerical models that are built in Aspen customer modeller and integrated in Aspen Plus (TM). Two types of combined cycles are compared: a combined cycle consisting of a two-staged combination of IT-SOFC and HT-SOFC and another consisting of two stages of IT-SOFC. in both combined cycles, the anode flows of the first and second stage fuel cell stacks are connected in parallel while the cathode flow is connected serially. The simulation results Show that a single-staged HT/SOFC and IT/SOFC have an efficiency of 57.6% and 62.3%, respectively. A combined cycle of two-staged IT-SOFC can give 65.5% under standard operational conditions. Furthermore, by optimizing the heat recovery and the gas turbine use, the efficiency can go tip to 68.3%. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.