Resistance and capacitance of the ZnO-SiO2-Au device appreciably respond to changes in O-2 partial pressure under strong UV illumination (10 mW/cm(2)). From complex impedance plots under the strong UV illumination, values of resistance of the ZnO film are estimated to be 300 and 50 k Omega in Oz and in Ar, respectively, and values of resistance of the ZnO-SiO2 interface at 0 V are estimated to be 1000 and 280 k Omega in O-2 and in Ar, respectively. Plots of Cp(-2) vs V in the dark, where C-p is the capacitance of the ZnO-SiO2 interface and V is a bias voltage, indicate that the band bending in O-2 is larger than that in Ar by 0.25 eV;and that the carrier density (5 x 10(17) cm(-3)) of the ZnO film in O-2 is the same as in Ar. When the UV illumination is turned off, a remarkable recovery of resistance measured at 100 Hz is observed at -2 and 0 V in Oz, while no recovery is observed in Ar. The response of the resistances of both the ZnO film and the ZnO-SiO2 interface to changes in the Oz partial pressure is ascribed to a change in the band bending caused by adsorption and photon-stimulated desorption of oxygen.