We investigated the admittance spectra of resistive switching Pt/Nb-doped SrTiO3 single-crystal junctions at different resistance states in air and vacuum. The analyses showed that the carrier lifetime at the traps was largely varied depending on the resistance state, indicating the surface potential modification. The ambient dependence suggested that the charges at the trap states were affected by the oxygen adsorption/desorption at the surface. The conductance spectroscopy method clearly revealed the importance of the interface trap states in the resistive switching behavior. (C) 2012 Elsevier B.V. All rights reserved.