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.