The solid oxide fuel cell (SOFC) has much higher energy efficiency than combustion-based energy conversion. This efficiency, coupled with its environmentally friendly nature, makes it a favorable candidate as part of the solution for today''s increasing demand for energy spurred by economic development, population increase, and competition for limited fossil fuels. Out of all other types of fuel cells, the SOFC shows higher efficiencies and greater fuel flexibility because of its higher operating temperature. The concept of generating electrical power from SOFCs fueled by coal-derived syngas as a clean coal technology has been well established within the SOFC research community. However, some of the impurities contained in syngas have been identified as potential threats to SOCF performance and durability. The study reported in this book was made to determine the effects of mercury as a contaminant in coal syngas on the performance of a Ni/YSZ anode of a planar SOFC. This book covers necessary thermodynamics, electrochemistry, loss mechanisms, and electrochemical techniques, as well as background, methods, and procedures for fuel cell testing.