Solar photo-catalytic process is an emerging and promising technology both as an alternative treatment to conventional wastewater treatment methods and enhancement of biodegradability of highly toxic and recalcitrant pollutants. In this study, results for the treatment of 3-indole butyric acid solutions using pilot scale solar photo-catalytic treatment process are presented. The effecting parameters, such as adsorption of 3-indole butyric acid on TiO2, pH, the initial concentration of 3-indole butyric acid and catalyst concentration, on the treatment of 3-indole butyric acid using solar photo-catalytic system were investigated. Solar photo-catalytic processes demonstrated high COD (>80%), TOC (>80%) and 3-indole butyric acid (>90%) removal efficiencies for the samples in this study. The increase of the 3-indole butyric acid concentration from 10 to 150 mg/L decreases the removal rate constant from 0.0757 to 0.0088 1/min in 240 min of oxidation using 100-1500 mg/L TiO2 at 3-9 pH.