In this paper, the DC diaphragm glow discharge (DGD) occurred around the small hole on quartz tube between two submersed graphite electrodes and the onset of DGD was systematically investigated. It was found that critical voltage (V-D) decreased with the increasing conductivity, and then maintained at about 620 V. When the hole diameter increased from 1.0 mm to 25 mm, H2O2 formation and AO discoloration in anolyte increased with the increase of the hole diameter. In addition, the effect of electrolyte constituents on H2O2 formation and AO discoloration in anolyte induced by DGD was also studied. The concentration of H2O2 and AO discoloration in anolyte was close in inert electrolyte such as Na2SO4 and Na2HPO4 solution. The concentration of H2O2 and AO discoloration rate in Na2CO3 and NaAc solution was lower than those in Na2SO4 and Na2HPO4 solution, due to their capture ability for (OH)-O-center dot. However, NaCl showed enhancing effect on AO discoloration, although it consumed a certain amount of H2O2. The energy efficiencies of AO discoloration and H2O2 formation were also compared with those of other DGD reactor. (C) 2012 Elsevier Ltd. All rights reserved.