Platinum dual-disk microelectrodes with interelectrode gaps of 5-40 mu m were constructed for the first time by fixing two 60 mu m diameter platinum wires onto a glass slide with epoxy resin as a fixative. The collection efficiency, shielding and feedback factors were investigated in detail. The collection efficiency is related both to the geometry gap width and the method used to polish the electrode and increases with a decrease of the gap width. The collection efficiency for a dual-disk microelectrode with a gap of 5 mu m is 44.4%. The collector current decreases with an increase of the concentration of the ascorbic acid added to the solution of 2.0 mmol l(-1) K4Fe(CN)(6), because the follow-up chemical reaction between Fe(CN)(6)(3-) and the ascorbic acid causes a decrease of the concentration of Fe(CN)(6)(3-) diffusing to the collector. Shielding and feedback factors of this device are very small. The fluctuation of the collector current was observed due to the influence of the natural convection or vibration, ?The effects of temperature and stirring were also discussed. Results show that both the temperature and stirring result in an increase of the generator current. However, the collector current rises with the temperature and falls rapidly with an increase of the stirring rate.