The thermal stability of Ti3AlC2/Al2O3 composites in high vacuum was investigated. On the sample surface, Ti3AlC2 can decompose with the formation of TiC0.67 and gaseous Al at first, then Ti evaporation results in the irregular morphology of non-stoichicometric TiCx. At the same time, the amount of Al2O3 particles becomes less with increasing the soaking time. Finally, Al2O3 particles disappear and a layer of non-stoichiometric TiCx, forms on the sample surface. But the bulk Ti3AlC2/Al2O3 composites always keep stable during the vacuum treatment. (c) 2007 Elsevier B.V. All rights reserved.