The role of TiO2 in the photocatalytic processes of polluted waters treatment is considered and mechanism of its action is discussed. It is shown that elaboration of modified complex systems based on titanium oxide is a perspective way of photocatalysis development. The electrochemical methods of nanodispersed highlyordered TiO2 tubes production are discussed, including modification of nanotube surface with thin metal coatings. Application of titanium dioxide in heterogeneous processes of decomposition of toxic persistent water pollutants (such as benzothiazoles) has demonstrated their high efficiency.