Titania dioxide of anatase structure was doped with iron and a residue carbon through the mixing of TiO₂ with FeC₂O₄ in the ratio of 10:1 and heating at different temperatures, 500-800^oC under Ar flow. The pure titania dioxide and prepared samples were used for humic acids decomposition under UV irradiation. It was proved that humic acids were decomposed through the preliminary adsorption on the photocatalyst surface, which was confirmed by FTIR measurements. Modification of TiO₂ by iron doping, especially at low temperature of heat treatment, caused increased adsorption of humic acids on its surface and enhanced photocatalytic activity. At lower temperatures of heat treatment iron was present in the form of magnetite and hematite whereas at higher temperatures was inbuilt in TiO₂ lattice and formed FeTiO₃ phase, which showed lower photoactivity. Degradation of humic acids was controlled by the particle size measurements in the solution, and also by UV absorbance at 254 nm, Fluorescence Spectroscopy and Total Organic Carbon.