Elucidating internal thermal conditions of high-temperature solid oxide fuel cell (SOFC) stacks is essential for obtaining a substantial thermal efficiency and reliability for long-term operations prior to their commercialization. To examine simultaneous heat transfer and its generation and their effect on the local thermodynamic state, a high-fidelity physical model that resolves spatially the three-dimensional structure of planar, anode-supported SOFC stacks is used in this study. Results show that thermal conduction through metallic interconnects plays a key role in transferring the heat produced by joule heating and electrochemical reactions and thus determining the internal thermal conditions. The heat generated from the electrolyte and thin reactive electrode layers is transferred to the interconnect predominantly by gaseous convection and conduction through materials in the anode and cathode, respectively. The interconnect subsequently transports this heat conductively towards gas inlets and/or surrounding repeating units, influencing temperature increments, its profile and hot spot formation. Its effect on the internal thermal conditions was further examined by a parametric study with respect to the thermal property and geometry of the interconnect which determine its thermal resistance. They indeed affect significantly heat generation and its transfer within the cell, through its boundaries, between repeating units and to incoming gases. (C) 2016 Elsevier Ltd. All rights reserved.