Zinc oxide (ZnO) nanorod arrays made by the hydrothermal method were treated with hydrogen peroxide (H2O2) solution through two different approaches. One is to immerse ZnO nanorod sample into H2O2 solution. The other is a pre-treatment of spin-coating H2O2 solution on the seed layer before the growth of the ZnO nanorods. In the first approach, we found that the ultraviolet (UV) emission peak of the ZnO nanorod photo luminescence (PL) spectra was strongly dependent on the immersion time. In the second approach, the H2O2 solution influences not only the quality of the seed layer, but also the amount of the oxygen interstitial defects in the ZnO nanorods grown thereon. As a result, the UV emission intensity from the ZnO nanorods is enhanced almost five times. The ZnO nanorod arrays with few oxygen interstitial defects are prepared by the hydrogen peroxide treatment and expected to enable the fabrication of optoelectronic device with excellent performance. (C) 2008 Elsevier B.V. All rights reserved.