Abstract In this study UV/TiO 2, electro-Fenton (EF), wet-air oxidation (WAO), and UV/electro-Fenton (UV/EF) advanced oxidation processes (AOPs) have been applied to degrade Reactive Red 120 (RR120) dye in aqueous solution. The most efficient method on decolorization and mineralization of RR120 was observed to be WAO process. Photocatalytic degradation of RR120 by UV/TiO 2 have been studied at different pH values. At pH 3 photocatalytic degradation kinetics of RR120 successfully fitted to Langmuir–Hinshelwood (L–H) kinetics model. The values of second order degradation rate ( k″) constant and adsorption constant ( K) were determined as 4.525 mg L −1 min −1 and 0.387 L mg −1, respectively. Decolorization efficiency observed in the order of WAO>UV/TiO 2=UV/EF>EF while WAO>UV/TiO 2>UV/EF>EF order was observed in TOC removal (mineralization). For all AOPs, it was found that degradation products in reaction mixture can be disposed safely to environment after 90 min treatment.