The surface characteristics of ternary ceramic powders in the system TiO2-SiO-Al2O3 prepared by a sol-gel technique were studied through nitrogen gas adsorption at liquid nitrogen temperature and application of the Brunauer-Emmett-Teller (BET) equation. The total surface area, total pore volume and pore radius of the powders were calculated through the construction of plots relating the amount of nitrogen gas adsorbed V-1 and the thickness of the adsorbed layer t (V-1 - t plots). These results permitted the detection of the different types of pores present in the samples. In a first approximation, the V-1 - t plots seem to demonstrate the correctness of the results obtained for the total specific area of the investigated samples. The influence of thermal treatment (drying, calcination) on the surface characteristics of the investigated powders was assessed.