The tunable recovery time and photosensitivity are achieved by controlling the concentration of oxygen vacancies on the surface of ZnO-nanowire (ZnO-NW) photodetector (PD) through a hydrothermal treatment in pure water. Performance instability originates from the interaction of oxygen vacancies near ZnO surface with the atmosphere during service. A novel conception of decreasing the concentration of oxygen vacancy for decreasing photoresponse time is proposed and achieved by a hydrothermal treatment. The rationale can be widely used for compensating oxygen vacancies of nanostructures with complex morphology at low temperature. (C) 2013 Elsevier B.V. All rights reserved.