The simple technique of extracting oxygen radicals anion (O-) from an anode of yttria stabilized zirconia (YSZ) by applying a low electric field has been reported (Torimoto et al., 1997, 2000). The reports suggest that the importance of a microstructure device could realize a highly energy-efficient production of O- at a low electric field, because the energy efficiency of O- production is defined to divide energy used for dissociation of oxygen molecule by input power (epsilon = const./V). Research on a microstructure device on a YSZ anode has been carried out. The new anode layer consists of a gold/SiO2/gold sandwich on a YSZ substrate having a regular array of open micron-sized pores, The typical film thicknesses of the sandwich are 1 micron, 5 micron and 1 micron from the top gold layer. Moreover, a major fraction of negatively charged species passing through the holes in the top electrode are collected by a relatively distant external electrode. By applying a few volts to the sandwich structure, oxygen radical anions were observed using a quadrupole mass spectrometer, It is, therefore, considered that the microstructure device on the YSZ anode will be a highly energy efficient device for producing O-.