Na-doped ZnO nanowires with an average diameter of similar to 40 nm have been fabricated by a thermal decomposition route at temperatures around 400 degrees C. Their properties have been investigated using X-ray diffraction, field emission scanning electron microscope, Raman spectra, photoluminescence spectra and Xray photoelectron spectra. Photoluminescence spectra showed that the as-synthesized ZnO samples exhibited strong visible emission with a major peak at 420 nm. Furthermore, intensity of the visible emission at 420 nm enhanced as the increase of Na concentration. The improvement of visible emission in the Na-doped ZnO samples should be a result of the surface defects increased by doping of Na in ZnO. Their antibacterial activities were also evaluated by determination of minimum inhibitory concentration (MIC) against Escherichia coli 25922 in vitro. Antibacterial tests indicated these nanomaterials showed good antibacterial properties after UV illumination for a short time. (C) 2010 Elsevier B.V. All rights reserved.