The reactions that took place in the spinel and in the carbon-spinel interface at high temperatures (1250-1800 degrees C) under low oxygen partial pressure (P-O2 <= 10(-16) MPa) are described in detail. Scanning electron microscopy equipped with microanalysis by energy dispersion (SEM-EDS) and X-ray diffraction lattice parameter have been used to determine the extent of solid solubility of Al2O3 in MgAl2O4. The Al2O3/MgO spinel ratio at different temperatures in air and packed with carbon were also determined. The behavior of spinel under these reducing conditions was discussed. (c) 2006 Elsevier B.V. All rights reserved.