A novel sequencing batch internal micro-electrolysis reactor (SIME) was specifically designed to treat mature landfill leachate. The idea of simulating the biological process of a sequencing batch activated sludge reactor (SBR) was employed in the design of the new reactor. The innovative concepts behind this design are the combination of the processes of reductive internal micro-electrolysis (IME) without aeration and oxidative IME with aeration, and the integration of electro-aggregation and electro-coagulation. The automated operating system in this reactor is centralized automation which rewards for safe control, convenient operation and the possibility of commercial application. The SIME reactor exhibited a COD removal efficiency of 86.1% for mature landfill leachate in this study, which is much higher than that of conventional treatments, such as electrolysis, coagulation-sedimentation, and the Fenton process. A pilot-scale experiment showed that the reactor was also particularly efficient in the removal of color, humic acids, and metal ions. The BOD5/COD ratio of the leachate was significantly improved after the treatment. All of these results show that the SIME reactor is a promising new technology because it is efficient and automated, and has the potential to be applied to the practical treatment of mature landfill leachate. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.