Terephthalic acid (TPA) wastewater is traditionally being treated by biological method. This study investigates the degradation of three major toxic target organic species, namely terephthalic acid (TPA), isophthalic acid (IPA), benzoic acid (BA), present in the TPA wastewater, by several advanced oxidation processes. The performance of three main oxidation processes such as photofenton oxidation (UV-H(2)O(2)-Fe), photocatalytic ozonation (UV-O(3)-Fe) and photofenton ozonation (UV-O(3)-H(2)O(2)-Fe) were studied. Studies were conducted with and without dilution of TPA wastewater. Photofenton ozonation was found to be most efficient by achieving almost complete destruction of all the three target organics in less than 30 minutes of reaction. In combining several oxidation processes, a comparative study was also carried out between one step addition of oxidants and stepwise addition.