Vibrational Raman spectroscopy coupled with voltammetry and impedance measurements was used to explore the effects of chlorine on solid oxide fuel cell (SOFC) performance and durability. SOFC anodes were exposed to 110 ppm dry CH3Cl at 650 degrees C for up to four hours while intermittently exposing the cell to methane for ten minute intervals. In these experiments Raman spectroscopy was used to monitor carbon accumulation kinetics. Electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) measurements performed under CH4 following 1 hour of exposure to CH3Cl showed marked degradation This degradation was less apparent when the SOFC was operated with H-2 in the presence of CH3Cl. With methane and CH3Cl, peak power diminished at a rate of 14% per hour. Observable carbon accumulation during CH3Cl exposure became less pronounced over time. Eventually, carbon formation was suppressed completely suggesting that the primary effect of the Cl contaminant was deactivation of the Ni catalyst with respect to CH bond dissociation. SOFC performance with H-2 in the presence of CH3Cl remained largely unchanged. Interestingly, these effects of Cl on SOFC performance with methane proved partially reversible as electrochemical performance and carbon accumulation behavior were recovered upon removal of the CH3Cl from the fuel feed. (C) The Author(s) 2015. Published by ECS. All rights reserved.