An electroactive coating was deposited on the surface of carbon microelectrodes from solutions containing Pb(NO3)(2), Na2IrCl6 and KNO3 by scanning their potentials from 0.0 to 1.15 V. The coating, believed to be IrO2 entrapped inside a PbO2 matrix, catalyzes oxidation of glucose, and other carbohydrates (e.g. mannose), in a phosphate buffered saline solution at pH 7.4. The microelectrodes coated with iridium and lead oxides were used as amperometric detectors at 0.75 V (versus a sodium saturated calomel electrode) for flow injection analysis of glucose samples. The linear dynamic range extended from 0.1 mM up to at least 20 mM, and the detection limit was 50 mu M for glucose. The stability and selectivity of the oxide-modified electrodes were improved by application of Nation(R) coating. The response of the Nafion(R)-coated electrode to 15 mM glucose was stable for four days.