Reformed fuel gases utilized in solid oxide fuel cells (SOFCs) contain significant amounts of carbon in the form of CO and CO2. Alloys, Such as ferritic stainless steels, which are utilized as interconnect materials in intermediate temperature SOFCs may, therefore, be susceptible to carburisation. Long-term exposure of ferritic stainless steel, with and without a nickel protective layer, to simulated carbon-containing fuel gas environments has been Studied. Optical and electron microscopy (both SEM and TEM) techniques were utilized to characterize the microstructures prior to and after carburising. (C) 2003 Elsevier Science B.V. All rights reserved.