Branched ZnO nanowires were synthesized using a three-step process: 1) synthesis of ZnO nanowires by the thermal evaporation of a mixture of ZnO and graphite powders on Au-coated C-plane sapphire substrates for 1 h, 2) deposition of Au on the as-synthesized ZnO nanowires, and 3) resumption of the thermal evaporation process for 10 min. The multiple-networked branched ZnO nanowire sensors exhibited far superior NO2 gas sensing properties than the unbranched nanowires. The origin of the enhanced NO2 gas sensing properties is also discussed. (C) 2013 Elsevier B. V. All rights reserved.