Highly efficient H2O2 generation is greatly demanded in electro-Fenton process for organic pollutants degradation. In the present work, a novel H2O2 generation reactor using dual gas diffusion electrodes (GDEs) as cathodes was put forward, which was confirmed to be more cost-effective in H2O2 generation rate, O-2 utilization efficiency and energy consumption in comparison with other carbonaceous materials and reactors. The catalyst layer in GDE was characterized and optimized, and the accumulation of H2O2 reached to 566 mg/L in 0.05 M Na2SO4 at a current density of 7.1 mA/cm(2) and air flow rate of 0.5 L/min after 180 min. The operational parameters such as current density, pH and air flow rate were optimized, and after 10 times used the production of H2O2 was confirmed to be stable. This novel reactor was tested to degrade tartrazine, and even for a high initial concentration of 1000 mg/L, it could be completely decolorized within 60 min while the TOC removal efficiency could reach 66.1% within 120 min with a mineralization current efficiency of 65.1%, indicating its potential for the treatment of high-concentrated wastewaters. (C) 2014 Elsevier B.V. All rights reserved.