Thermolytic decomposition in a chloride-acid medium of a titanium aquacomplex precursor solution [Ti(OH2)6]3+•3Cl¯ as a result of its boiling at a temperature of (110-114) 0С is accompanied by precursor hydrolysis and the formation of hydrate molecules Ti(OH)3Cl•2Н2О, which, as a result of condensation, provide the formation of rutile ТіО2 with rod-shaped particles (30-80) nm long and (8-20) nm in diameter, combined into flower-shaped associates with a diameter of (200-280) nm. IR spectroscopic studies of the precursor hydrolysis products and the synthesized oxide material show that the geometric parameters of ТіО5Cl octahedra of Ti(OH)3Cl •2Н2О hydrate molecules are close to those of ТіО6 octahedra of ТіО2 rutile. The average Ti-O interatomic distance of octahedra of titanium-containing hydrate molecules is a kind of template that directs the process of ТіО2 crystallization towards the formation of rutile. Rutile ТіО2 nanopowder synthesized in this way is an effective photocatalyst for the photooxidation of organic dyes in an aqueous medium by UV radiation. The photocatalytic activity of the synthesized rutile ТіО2 was determined by neutralization of Congo Red (CR) dye dissolved in an aqueous medium. The effectiveness of TiO2 was studied by examining the effect of TiO2 amount and Н2О2 concentration. It has been established that complete bleaching of the dye is achieved in just 10 minutes of UV irradiation at a photocatalyst concentration of 1.5 g/L, an Н2О2 concentration of 5 mM, and an initial CR dye concentration of 5 mg/L, at reaction rate constant of 2.1959 min-1.