Two aluminium titanate (AT) ceramics containing magnesium and iron were sintered to study their high-temperature mechanical property and thermal stability. Both materials exhibited a pronounced inelastic stress-strain behaviour which is caused by extensive microcracks. The microcracking also led to an increasing R-curve behaviour which was measured in the Mg-AT material in the as-sintered state. At 1000 degrees C, crack healing took place which led to an increase in the strength and Young＇s modulus. At 1100 degrees C, the glassy phase started to soften which resulted in a reduction of the strength and Young＇s modulus. Thermal stability was assessed after annealing at 1000, 1100 and 1200 degrees C for 250 and 1000 h in air. Although the Fe-AT material did not show any significant decomposition and degradation in mechanical properties, the Mg-AT material annealed at 1000 and 1100 degrees C showed pronounced decomposition into corundum and rutile. The decomposition led to a brittle fracture, but increased the strength and Young＇s modulus. Both materials showed a lower coefficient of thermal expansion (<0.2 x 10(-6) K-1) than that of stoichiometric aluminium titanate. The results are discussed with respect to the microstructure and phase relationship.