The structural characteristics of supported MoOx, species inherent over a high TiO2 content silica-titanic mixed-oxide support (1:l molar ratio), combined with the structural effects that are induced by an alkali promoter, are the primary focus of this investigation. The catalysts were prepared using a "one-pot" modified sol-gel/coprecipitation technique that distributes the molybdenum precursor throughout the Si/Ti support network as it forms during gelation. The Si/Ti 1:1 mixed-oxide support is in a state of nanodispersed titania (anatase) over silica. With the introduction of molybdenum and successive levels of alkali promoter, the dispersion of titania decreases as does the interaction of TiOx species with silica. Concurrent with this change is the observation of an enhanced interaction of the Moo, species with silica. Correlation is found among the propane ODH reactivity, the surface coverage of oxidic molybdenum species, and the nature of the Si/Ti support. H-1-Si-29 CP-MAS NMR data and DRIFT spectra taken in the hydroxyl stretching region (3000-3900 cm(-1)) suggest that, with the addition of alkali, the three dimensionality of the silica support is changing to accommodate the change in MoOx surface structure. The presence of potassium significantly alters the dispersion of titania and the electronic structure of the surface MoOx domains, even before the formation of K-molybdate species is observed at higher K/Mo molar ratios. This electronic interaction is observed readily in the ESR spectrum of Mo(V) that is present in the dehydrated samples. Data suggest that surface-supported species, present as distorted octahedral MoOx, become the most distorted at low alkali levels (K/Mo = 0.07). The Moo, species at this level of alkali promotion, which experience a decrease in Lewis acidity, could tend to be more reactive toward electronegative Si-O- support ligands on the Si/Ti 1:1 support. The observed increase in propane ODH reactivity at low K/Mo molar ratios may be ascribed to a highly distorted structure sharing both titania and silica ligands.