Solid oxide fuel cells (SOFCs) working under direct reforming or catalytic partial oxidation may experience severe thermal gradients due to cooling or overheating at the fuel cell inlet. In this work, we show that the ohmic resistance measurement of thick electrolyte cells composed of smaller cathodes displaced along the opposite side of a full-size anode provides excellent results to evaluate the temperature gradients along cells submitted to such processes. Taking the catalytic partial oxidation of methane in single-chamber SOFC, as an example, we evaluate an overheating of more than 50 degrees C within the first centimeter length of the cell. (c) 2006 The Electrochemical Society.