A series of SiO2–TiO2 mixed oxides was prepared by the sol–gel route, and the influence of several important preparation parameters (Ti precursors, content, and calcination temperature) on the Si–O–Ti connectivity, coordination of titanium and surface acidity has been studied using various analytical techniques. The solids obtained were largely amorphous and characterized by Ti enrichment on surfaces with low titanium content; however, the addition of titanium greater than 50 mol% into the SiO2 matrix led to significant phase separation of crystalline anatase. The Ti atoms are tetrahedrally coordinated with Si/Ti ratios higher than 10 and gradually enter into octahedral positions in the silica matrix with further increase in the titanium content. High-temperature treatment can break Si–O–Ti linkages and eliminate hydroxyl groups, resulting in a decrease in acid site density.