with or without 10 mM glu-cose. Three anodic peaks (1, 2 and 4) attributed to the oxidation ofglucose. The decrease in current after the peak (2) should be dueto the formation of platinum oxide, which competes for adsorp-tion sites with glucose and, in turn, inhibits the electro-oxidationof glucose as well. During the negative potential scan, the oxida-tion of glucose is suppressed in the high potential range because ofthe presence of surface oxide. With the reduction of Pt oxide (3),more surface-active sites are available for the oxidation of glucose,resulting in a large and broad oxidation peak (4). These results canbe explained by the well-accepted mechanism of the oxidation ofglucose on a Pt electrode in neutral media [9,25,27], as we could notfind these peaks in the absence of glucose. From the above results,we can obtain that Pt0.7Co0.3/C has the strongest electrocatalyticactivity toward the oxidation of glucose.