Solid oxide fuel cells (SOFC) can use wide varieties of fuels such as hydrogen, carbon monoxide, hydrocarbons, alcohols as well as synthesis gases from natural gas, biogas and petroleum. Using such a wide range of fuels introduces the risk of unwanted impurities, which can affect the function of the SOFC. One of the known impurities is sulfur which is a well known catalyst poison. This work deals with the effect of H2S containing fuel gas on SOFC stack performance as well as regeneration processes and their underlying mechanisms.