Wastewaters present a significant ecological problem because of different organic compound content whose presence is undesirable so they cannot be discharged into effluents without prior adequate treatment. Besides traditional methods of treatment, advanced oxidation processes (AOP) could be one of the possibilities for the treatment of such type of wastewaters. One method of treatment is photocatalysis, which involves the development of new polymer nanocomposites with extended photocatalytic activity moved to the visible region of the UV/Vis spectrum of solar irradiation. In this work the polymer nanocomposites were synthesized with poly(3,4-ethylenedioxythiophene) in the presence of TiO2 in order to obtain the photocatalyst. The effect of the various oxidants (APS and FeCl3) on the structure of nanocomposite photocatalyst was studied, which results in different photocatalytic activity. Synthesized nanocomposite photocatalysts were characterized by FTIR spectroscopy to compare the chemical composition, X-ray diffraction analysis (XRD) was used to analyse the crystal structure, and the conductivity of the obtained composite was determined. Photocatalytic activity was investigated by monitoring the removal of dyes, Reactive Red 45 (RR45) and Acid Blue 25 (AB25) under the UV-A irradiation. Removal of dyes and their change of discoloration in the water were monitored by measuring the absorbance with UV/VIS spectrophotometer. Removal of dyes, i.e. its mineralization (complete decomposition) was followed by the determination of total organic carbon (TOC). The results showed that the higher removal of colorization for both dyes (RR45, AB25) was obtained by PEDOT/Ti-1 sample. Synthesized photocatalysts showed approximately the same degree of dyes mineralization (approximately equal value of TOC) as well as the pure TiO2 catalyst.