Ordinary electrolysis developed spontaneously to contact glow discharge electrolysis (CGDE) at sufficiently high voltage, with glow discharge taking place around a thin platinum anode which was in contact with electrolyte solution. During this transition, the critical voltage (V-D) was an important parameter for the onset of CGDE. The results indicated that V-D decreased with the increasing conductivity and then maintained a certain value. The different dimension and material of cathode had little effect on V-D. When the electrolyte conductivity was 5.0 mS/cm, V-D was hardly affected by electrolyte composition. And the concentrations of H2O2 producing in the anolyte were close in different inert electrolyte. However, the concentrations of H2O2 in NaCl, NaAc, Na2CO3 and NaHCO3 solution were lower than that in Na2SO4 solution. And the concentration of H2O2 in the anolyte was also decreased by adding a minute amount of CH3OH. (C) 2010 Elsevier Ltd. All rights reserved.