Molten Carbonate Fuel Cells (MCFCs) can be used as CO2 separators in fossil fuel power plants. Fossil fuel power plants emit flue gases with SO2 contaminants, thus the influence of SO2 on the operation of MCFC is investigated both theoretically and experimentally. The influence of SO2 contaminants (up 680 ppm) on MCFC performance was examined. The experimental investigation revealed there is a boundary limit where SO2 contamination could increase the MCFC voltage. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.