Significant contribution of three-phase boundary for oxygen reduction reaction at a gold disk electrode in hanging meniscus configuration in dimethyl sulfoxide (DMSO) solution was demonstrated. While cyclic voltammograms (CVs) with symmetrical shape representing quasi-reversible kinetics were obtained for oxygen reduction reaction (ORR) at a Au disk electrode in an ordinary configuration when it was fully immersed in an O-2 saturated 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF(6)) DMSO solution, asymmetric CVs with enhanced ORR current were obtained at a Au disk electrode in the hanging meniscus configuration. Origin of this feature was investigated at a gold wire electrode, which was immersed partly in the solution, in detail by changing the concentrations of O-2 in the gas phase and in solution independently as well as the immersion depth. All the results confirm that the ORR at the three-phase, O-2 gas/Au electrode/electrolyte solution, boundary contributes dominantly to the observed current in the hanging meniscus configuration. (C) 2013 Elsevier B.V. All rights reserved.