Abstract Large-scale, high density silicon oxide nanowires have been synthesized on Si substrate with liquid phase Bi as a novel catalyst under H 2 flow at 1100 °C. The length of the SiO x nanowires is in the range of several tens to hundreds of micrometers, and the diameters of nanowires are 20–200 nm. The result of transmission electron microscopy shows that the SiO x nanowires are amorphous. The formation process of SiO x nanowires is related to the solid–liquid–solid growth mechanism. Photoluminescence spectrum of SiO x nanowires shows two peaks at 347 and 457 nm under the 220 nm ultraviolet fluorescent light excitation and ultraviolet–visible absorption spectrum of SiO x nanowires shows strong absorption peak between 200 and 300 nm.