The current study applied Fe(III)-carboxylates, like Ethylenediamine tetraacetic acid (EDTA), oxalic acid and citric acid, in photo-Fenton reactions in the treatment of sanitary landfill leachate using simulated solar irradiation. The complex formation is justified by drawbacks identified in conventional Fenton and photo-Fenton reactions, such as the acidification step that precedes a decrease of the organic load before the initiation of the oxidation. By employing a lab-scale photo-reactor to treat osmosis concentrate landfill leachates, the main operational parameters, like solution pH, iron and chelating agent concentration, H2O2 consumption and required energy were evaluated as a function of decoloration and decrease of 254 nm absorbance in the sanitary landfill leachate. The best results were found with the photo-reactor operating at pH 6.0, 100 mg Fe(III):EDTA L-1; consuming 275 mM H2O2 and demanding about 8 kJUV L-1, providing the total decoloration and 80% reduction of the 254 nm absorbance in landfill leachates. Under such conditions the decrease of the organic load was satisfactory, including the reduction of dissolved organic carbon (DOC), total dissolved nitrogen (TDN), 5th day biochemical oxygen demand (BOD5) and chemical oxygen demand (COD), and probably improving the treatment conditions in terms of biodegradability of the sanitary landfill leachate (BOD5/COD ratio).