This work reports a novel process to synthesize copper hydroxyl nitrate/zinc oxide composites (Cu-2(OH)(3)NO3/ZnO), and their application as a highly effective and reusable catalyst for wet oxidation of methyl orange (MO) under ambient conditions. No additional air or oxygen flow is required. Using a metal oxide assisted method, the Cu-2(OH)(3)NO3/ZnO composites were hydrothermally obtained by varying the Cu:Zn mole ratio (2:1,4:1, and 6:1) and the structural, chemical and surface properties of the composites were investigated. Decolorization of 500 ppm MO can be effectively catalyzed by the Cu-2(OH)(3)NO3/ZnO composite (Cu:Zn = 4:1) with the color, chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiencies being greater than 99%, 98% and 94%, respectively, after 20 min treatments using the catalyst loading of 3 g L-1. Results from systematic catalytic activity tests strongly suggested that MO was oxidized by oxygen dissolved in the dye solution, and that the degradation pathway of MO possibly occurred through radical and H2O2 generation. The application of highly efficient Cu-2(OH)(3)NO3/ZnO catalysts in wastewater remediation may be attractive alternative to existing oxidation catalyst systems as they are low-cost, simple to prepare, feasible to operate under ambient conditions. (c) 2012 Elsevier B.V. All rights reserved.