TiOx-VOx mixed oxides supported SBA-15 catalysts were prepared in a very controlled way by the designed dispersion method (MDD) using acetylacetonate complexes. The Ti and V active centers are generated by the MDD of the TiO(acac)(2) and VO(acac)(2). The process consists of the adsorption and subsequent thermolysis of the Ti-V complexes. A careful selection of synthesis conditions allows us to modify the mutual interaction of the Ti and V centers and the interaction of the active centers with the silica support. The decomposition of the anchored complexes and the conversion of the physisorbed species toward covalently bonded TiOx-VOx surface groups have been studied by using a home-built in-situ IR transmission cell. IR seems to be the most suitable technique to follow the calcination process that is required to understand the reaction mechanism. During the thermal conversion, the Ti-V/acac precursor is converted toward supported mixed oxide. Additional characterization was done by FTIR-PAS, TGA, chemical analysis, as well as XRD, FT-Raman, and N-2 adsorption measurements.