To achieve both oxidation reactions at a more negative potential and better reactions in electrocatalytic glucose oxidation, AuCu alloy nanoparticles were synthesized and their activities for glucose oxidation in alkaline solution were investigated by voltammetric and controlled-potential electrolysis studies. Decanethiol-encapsulated (DT-) Au(nano), DT-Au(97)Cu(3) (m: atomic%), and DT-Cu(nano) nanoparticles were synthesized, and their core sizes were determined to be 2 (+/- 1), 2 (+/- 1), and 4 (+/- 2) nm, respectively. To remove the DT monolayer from the DT-Au(nano), DT-Au(97)Cu(3) and DT-Cu(nano) nanoparticles, nanoparticle-modified plastic-formed carbon plate (PFC) electrodes were heated at 300 degrees C for 2 h. Elimination of the DT was confirmed by FT-IR and XPS measurements. The surface metal atomic content ratios of DT-Au(97)Cu(3) eventually changed to Au(77)Cu(23), after the heat-treatment. The voltammetric behavior of electrocatalytic glucose oxidation at the Au(77)Cu(23) nanoparticle-modified electrodes in alkaline solution was similar to the Aunano nanoparticle-modified electrodes, in which the potential was more negative than a Cu(nano) nanoparticle-modified electrode and bulk-like Cu electrodes. Upon controlled-potential electrolysis, Au(77)Cu(23) nanoparticle-modified electrodes gave gluconolactone and formate as main products, which indicated that electrocatalytic oxidation, was promoted in comparison with the Au(nano) nanoparticle-modified electrodes. It is concluded that Au(77)Cu(23) nanoparticles have both advanced properties of Au(nano) and Cunano nanoparticles for glucose oxidation. (C) 2008 Elsevier B.V. All rights reserved.