Doped supports were fabricated by dry impregnation of γ-A1203 with various amounts of MNO3 (M+: Li+, Na+, K+, Rb+ and Cs+). A quantity of molybdenum(vi) corresponding to 12 % wt MoO3 was deposited on each modified support. The influence of the content of the modifier on the specific surface area of γ-A1203 was examined. A diminution in the specific surface area due to the toping has been observed. The magnitude of this effect generally increases with the modifier content. A model taking into account the above observation has been postulated. The dispersion of the alkali cations on the γ-A1203 surface as well as the dispersion of Mo(vi) on the doped supports were studied using X-ray photoelectron spectroscopy:the dispersion of the alkali cations remains constant within the region 0.392-1.55 mmol of modifier per g of γ-A1203 followed by a considerable decrease at higher concentrations. As to Mo(vi),the variation in the dispersion with the dopant concentration depends on the kind of alkali cation. Thus, Li+ doping causes no considerable effect on the Mo(vi) dispersion. In contrast to that, doping by Na+, K+, Rb+ and Cs+ provokes a linear decrease in the Mo(vi) dispersion up to 1.55 mmol of the modifier per g of γ-A1203. Further increase in the dopant concentration has a quite weak effect on the dispersion. Diffuse reflectance spectroscopy measurements showed that the ratio of the K-M-S functions determined at 305 and65nm,F(R∞)305F(R∞)265,depends on the kind and content of the modifier: Li+ has no effect. The ratio mentioned decreases linearly with the Na+ (in the whole range of concentrations) and K+,Cs+and Rb+)up to 1.55 mmol per g of γ-A1203. A model postulated to explain the above mentioned X-ray photoelectron spectroscopy and Diffuse reflectance spectroscopy results, suggests the formation of surface alkali molybdates at the expense of the supported polymeric Mo (vi).