Titanium dioxide represents an effective photocatalyst for water and air purification and for self-cleaning surfaces. Additionally, it can be used as antibacterial agent because of strong oxidation activity and superhydrophilicity. TiO2 shows relatively high reactivity and chemical stability under ultraviolet light (� 400 nm) should allow the main part of the solar spectrum, even under poor illumination of interior lighting, to be used. Visible light-activated TiO2 could be prepared by metal-ion implantation, reducing of TiO2, non- metal doping or sensitizing of TiO 2 with dyes. This paper reviews preparation methods of doped-TiO2 with metallic and nonmetallic species, including various types of dopants and doping methods currently available. The mechanism of heterogeneous photocatalysis in the presence of TiO2 is also discussed.