Titanium dioxide (TiO2) was prepared by salt-gel synthesis and characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The composite photocatalyst was prepared by in situ synthesis of a conductive polymer polypyrrole (PPy) with the presence of titanium dioxide (TiO2). Synthesis of the polymer was carried out by chemical oxidation polymerization of pyrrole monomer (Py) with iron (III) chloride (FeCl3) as oxidant. The synthesized composite photocatalyst (PPy / TiO2) was modified (deprotonated) by soaking in ammonium hydroxide (NH4OH) of different concentrations for a different time. The reprotonation process was conducted by soaking in 0.01 M hydrochloric acid (HCl) at different times with the aim to recover the conductivity of PPy in the composite. The characterization of composite photocatalysts was performed by infrared spectroscopy with Fourier transforms (FTIR), thermogravimetric analysis (TGA) and by determination of the conductivity. The photocatalytic efficiency of synthesized composite photocatalysts before and after modification was tested by monitoring the removal of azo dye Reactive Red 45 (RR45) under simulated solar irradiation. The discoloration of water was monitored by measuring the change of absorbance by UV / Vis spectroscopy while the mineralization process (complete degradation) of the RR45 dye was determined by total organic carbon (TOC). The results show that the deprotonation resulted in decrease of PPy conductivity in the composite photocatalyst and is partially recovered by the reprotonation process. They also show that change in PPy conductivity has the influences on the photocatalytic activity, i.e. photodegradation of RR45 azo dye, which was lower.