Transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy techniques were used to investigate the structure of a TiOâ-ZrOâ binary oxide support and a VâOâ/TiOâ-ZrOâ catalyst. The TiOâ-ZrOâ (1:1 mole ratio) was obtained by a homogeneous coprecipitation method, and the 12 wt% VâOâ/TiOâ-ZrOâ catalyst was prepared by a wet impregnation method. Both samples were subjected to thermal treatments from 773 to 1,073 K in order to understand the temperature stability of these materials. The TiOâ-ZrOâ support was in an amorphous state when calcined at 773 K. However, the formation of the ZrTiOâ compound was noted at higher calcination temperatures characterized by a layer structure with a lattice spacing of ca. 2.87 â« due to the (111) plane of this compound. The VâOâ/TiOâ-ZrOâ catalyst when calcined at 773 K shows heterogeneity in the distribution of vanadium oxide species on the support surface. The TEM/EDX analysis further provides clear evidence for ZrVâOâ and TiOâ formation at 1,073 K calcination in agreement with X-ray diffraction observations.