An attractive feature of solid oxide fuel cell (soFq -based systems is the opportunity to combine the co-generation of electrical and thermal energy with carbon dioxide capture. CO2 from SOFC based systems can be easily captured for underground disposal and used for several technological applications including the production of synthesis-gas. In this work, the concentration of CO2 at the outlet of a system consisting of a pre-reformer, SOFC stack and a water gas shift reactor was investigated with respect to the operating parameters. The results demonstrate that a combination of very high CO2 content in the dry anode off-gas (50-65%) with a high electrical efficiency generated by the stack (>50%) can be obtained in a SOFC system fueled with natural gas. The stack fuel utilization (FU) was observed to be one of the major parameters which affects the exhaust gas composition, increasing the FU results in an increase of CO2 content on the dried stream. On the other hand, the amount of CO2 produced is not significantly influenced by the stack operating temperature. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.