A combination of ozonation and persulfate (O-3/S2O82-) was used to treat stabilized landfill leachate. COD, color, and NH3-N, ozone and persulfate doses, pH and reaction time were evaluated to define the optimum operational conditions. The results indicated that under optimum operation conditions (i.e. 210 min of ozonation, a COD/S2O82- ratio (1 g/7 g), and pH 10), the best removal values of COD, color, and NH3-N were 72%, 93%, and 55%, respectively. The biodegradability (BOD5/COD ratio) has improved from 0.05 to 0.29. The ozone consumption for COD removal was 0.76 kg O-3/kg COD. The results obtained by employing the combined use of persulfate and ozone were compared with those by employing ozone only and persulfate only. The results achieved with the combined use of persulfate and ozone were compared with those obtained with ozone only and persulfate only. The combined method (i.e., O-3/S2O82-) achieved higher removal efficiencies for COD, color, and NH3-N compared with other studied applications. Additionally, the combined of ozone/persulfate method proved to be more efficient than the combined use of ozone/Fenton in advanced oxidation processes in the treatment of the same studied leachate. (C) 2013 Elsevier B.V. All rights reserved.