Multiwalled carbon nanotubes (MWCNTs) were functionalized with acid treatment and thereafter gold-copper nanoparticles were electrodeposited on the MWCNTs by applying several repetitive scans, thus forming a Cu-Au-MWCNT/GCE interface. The electrochemical reduction of oxygen was studied on this modified electrode in 0.1 M NaOH solution. The electrocatalytic activity on the Cu-Au-MWCNT/GCE showed a tendency towards the O-2 reduction. The peak potential of O-2 reduction on the Cu-Au-MWCNT/GCE shifted ca. 70 mV higher positive potentials as compared to that of a polished glassy carbon electrode. A significant current enhancement was obtained on the Cu-Au-MWCNT/GCE compared to that of bare GCE, MWCNT/GCE, Cu-MWCNT/GCE and Au-MWCNT/GCE. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed in order to investigate the surface morphology and elemental composition of the modified electrode, respectively. (C) 2011 Elsevier B.V. All rights reserved.