An electrochemically formed gold oxide layer on the surface of a gold electrode was found to be a powerful and rather selective catalyst of glucose oxidation. Cyclic-voltammetric techniques were used to investigate the performance of the gold electrode in the presence of glucose at different concentrations up to 500 mg/100 cm3 (28 mM). A positive current peak due to the presence of glucose occurred during the cathodic sweep. The current values at these maxima showed a highly linear dependence on the concentration of glucose in several regions, depending on the medium composition. Chlorides, amino acids, and human albumin were observed to inhibit the reaction. On the other hand, urea and L-ascorbic acid contributed a stabilizing effect to the performance of the electrode. At 34 mg/100 cm3 (5.7 m M), urea did not affect the current, whereas ascorbic acid somewhat increased the output. The results of this study suggest that the layer of gold oxide on the gold electrode can be utilized for the detection of glucose, if a proper separation of the inhibitors is achieved.