To face worldwide energy-related environmental concerns, solid oxide fuel cell (SOFC) technology emerges as a promising route for clean and efficient production of electricity. Within this context, great efforts have been devoted to the development of SOFC devices able to run at intermediate temperatures and to retain electrochemical performance as good as in the high temperature regime. To this end, materials that have characteristics of mixed ionic and electronic conductors (MIECs) have been proposed as electrodes for SOFC applications. Among many proposed systems, MIEC electrodes based on strontium iron molybdenum oxide (Sr2Fe2–xMoxO6−δ) have been proven to be extremely efficient for intermediate temperature SOFC. However, to advance SFMO-based electrodes further, a detailed understanding of the physical and chemical processes involved and of the corresponding electronic and structural features is needed. As a first step in this direction, we investigate via quantum mechanics the Sr2FeMoO6 (SFMO) mater...