Wastewaters are significant environmental problem as they usually contain various types and quantities of pollutants. Such water is not suitable for use and it requires application of wastewater treatment technology to achieve satisfactory quality of treated water. The most common methods of wastewater treatments are biological, mechanical/physical and chemical methods. In case of organic contamination, the application of advanced oxidation processes (chemical methods) - the ozonization process, the Fenton process and the photocatalytic processes, proved to be the most effective. The photocatalysis process is based on degradation of contamination with the addition of photocatalyst under the influence of light, where titanium dioxide (TiO2) is used as a photocatalyst in this work. TiO2 contains a wide band gap and is therefore active only under UV light, which is why it can be synthesized in combination with conductive polymers which have a small band gap and thus they expand photocatalytic activity of TiO2 into the visible part of the spectrum. Apart from conducting polymers, the band gap can be reduced by adding ionomers - polyelectrolytes consisting of several ionic groups such as polystyrene sulfonic acid (PSS). In this paper, a nanocomposite photocatalyst of the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and titanium dioxide was synthesized by chemical oxidative polymerization method. Molar ratio of EDOT monomer and TiO2 was 1:30 while FeCl3 was used as an oxidant. Using the same procedure, but with the addition of polystyrene sulfonic acid (PSS), PEDOT/TiO2 nanocomposite photocatalysts were synthesized at 1:20 and 1:30 ratios. Characterization was performed by thermogravimetric analysis (TGA), infrared spectroscopy with Fourier transform (FT-IR) and by examination of morphological structure using scanning electron microscopy (SEM). The photocatalytic efficiency was tested by monitoring the removal of azo dye Acid Blue 25 (γ = 30 mg / L) in water at different pH (4.5, 6.3, 8.0) under the simulated solar or UV-A irradiation by measuring the absorbance at UV/Vis spectrophotometer. The results showed that dye degradation depends on EDOT and TiO2 ration while best efficiency was obtained at neutral or slightly acid conditions.