Specimens of SiC-AlN composites were preoxidized in air for 30 h at 1100, 1250, and 1370 degrees C. The Vickers microhardness (I-Iv) was tested at temperatures ranging from 25 to 1200 degrees C in Ar atmosphere. This work is mainly concerned with variations in oxidization and microhardness of SiC-AlN composites in different surface structures and properties.