A tialite ceramics (Al2TiO5) was synthesized at a temperature of 1500-degrees-C, incorporating CaF2, La2O3, SiO2 or kaolin and MgO additives. Its thermal stability was investigated by thermocycling in a reducing medium. The batches containing SiO2 or kaolin additives underwent a decomposition to rutile and corundum. A stabilized ceramic with added MgO was produced. X-ray and electron-probe microanalysis established the presence of Mg/Al, Ti(z)/O4, Al2-x-yTi1-xMgyO5 and Ca1-xLax/Al12-y-zMgyTiz/O19 solid solutions, which retained their chemical composition after thermocycling in a reducing medium.