The effects of V 2 O 5 , NiO, Fe 2 O 3 and vanadium slag on the corrosion of Al 2 O 3 and MgAl 2 O 4 have been investigated. The specimens of Al 2 O 3 and MgAl 2 O 4 with the respective oxides above mentioned were heated at 10°C/min from room temperature up to three different temperatures: 1400, 1450 and 1500°C. The corrosion mechanisms of each system were followed by XRD and SEM analyses. The results obtained showed that Al 2 O 3 was less affected by the studied oxides than MgAl 2 O 4 . Alumina was only attacked by NiO forming NiAl 2 O 4 spinel, while the MgAl 2 O 4 spinel was attacked by V 2 O 5 forming MgV 2 O 6 . It was also observed that Fe 2 O 3 and Mg, Ni, V and Fe present in the vanadium slag diffused into Al 2 O 3 . On the other hand, the Fe 2 O 3 and Ca, S, Si, Na, Mg, V and Fe diffused into the MgAl 2 O 4 structure. Finally, the results obtained were compared with those predicted by the FactSage software.