A simple method for synthesis of Na 0.65 WO 3 nanobelts by using sodium, as a catalyst, in soda-lime glass substrate was reported. The synthesized product was characterized and analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and ultraviolet–visible spectrophotometery. According to SEM observations, nanobelts with U-shape cross section grew between sodium–tungsten oxide islands. The thickness, width, and length of nanobelts were measured <100nm, between 300nm–3μm and 5–20μm, respectively. In addition, it was observed that some of the nanobelts were constituted from nanowires. Based on XPS analysis, more than 70% of the film surface was in W 6+ chemical state. XRD analysis determined that the sample was mainly composed of cubic Na 0.65 WO 3 phase with strong (011) and (001) diffraction peaks. Optical transmission and reflection of the sample in the visible and near-infrared wavelengths were measured around 15% and 2%, respectively.