A novel hydrogen peroxide-enhanced iron-carbon (Fe-C) microelectrolysis reactor was proposed for thepretreatment of mature landfill leachate. This reactor, combining microelectrolysis with Fenton process,revealed high treatment efficiency. The operating variables, including Fe-C dosage, H2O2concentrationand initial pH, were optimized by the response surface methodology (RSM), regarding the chemicaloxygen demand (COD) removal efficiency and biochemical oxygen demand: chemical oxygen demand(BOD5/COD) as the responses. The highest COD removal (74.59%) and BOD5/COD (0.50) was obtained atoptimal conditions of Fe-C dosage 55.72 g/L, H2O2concentration 12.32 mL/L and initial pH 3.12. Three-dimensional excitation and emission matrix (3D-EEM) fluorescence spectroscopy and molecular weight(MW) distribution demonstrated that high molecular weight fractions such as refractory fulvic-like sub-stances in leachate were effectively destroyed during the combined processes, which should be attributedto the combination oxidative effect of microelectrolysis and Fenton. The fixed-bed column experiments