A novel method for preparing a visible-light-driven mesoporous TiO2-xNx photocatalyst has been developed. It involves the in situ pyrolysis of the product from a chelation reaction under sonication between TiCl4 and ethylenediamine in an ethanol solution of the triblock copolymer F127. The as-prepared photocatalysts exhibit very strong photoactivity in the photocatalytic oxidation of methylene blue under irradiation in the visible spectral region. The samples were characterized by spectroscopic techniques including ultraviolet-visible light reflectance (UV-vis), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The effects of ultrasound on the physicochemical properties and photoactivity of mesoporous TiO2-xNx are discussed based on the characterization results. (c) 2009 Elsevier B.V. All rights reserved.