Iron-based oxides are considered as promising consumable anode materials for high temperature pyroelectrolysis. Phase relationships, redox stability and electrical conductivity of Fe 3−x Al x O 4 spinels were studied at 300–1773K and p(O 2 ) from 10 −5 to 0.21atm. Thermogravimetry/XRD analysis revealed metastability of the sintered ceramics at 300–1300K. Low tolerance against oxidation leads to dimensional changes of ceramics upon thermal cycling. Activation energies of the total conductivity corresponded to the range of 16–26kJ/mol at 1450–1773K in Ar atmosphere. At 1573–1773K and p(O 2 ) ranging from 10 −5 to 0.03atm, the total conductivity of Fe 3−x Al x O 4 is nearly independent of the oxygen partial pressure. The conductivity values of Fe 3−x Al x O 4 (0.1≤x≤0.4) at 1773K and p(O 2 ) ∼10 −5 to 10 −4 atm were found to be only 1.1–1.5 times lower than for Fe 3 O 4 , showing high potential of moderate aluminium additions as a strategy for improvement of refractoriness for magnetite without significant deterioration of electronic transport.