Model fer the dynamic simulation of dynamic behaviors of a solid oxide fuel cell (SOFC) is provided. This model is based upon (1) coupled mass and heat transfer characteristics and (2) important chemical reactions such as electrochemical and reforming reactions in high temperature fuel cells such as SOFC. It is found that the thermal inertia of solid materials in SOFC plays an important role to the dynamic behavior of cell temperature. Dynamic characteristics of cell voltage, power, and chemical compositions with different levels of load change are investigated.