This paper presents a simple one-step method for the fabrication of size-controlled Br-doped TiO2 nanoparticles via a hydrothermal method. The as-prepared Br-doped TiO2 photocatalysts were characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), N-2 desorption-adsorption measurements, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-vis) spectroscopy. The results indicate that the size of the Br-doped TiO2 nanoparticles would decrease with increasing Br-doping concentration. The minimum size of the nanoparticles is approximately 4 nm. The as-prepared Br-doped TiO2 photocatalyst is composed of the anatase and brookite phases. The Br-doping could efficiently narrow the band gap and broaden the visible-light response region. The dye on the surface of Br-doped TiO2 could improve the photocatalytic performance during cyclic utilization because of the dye activation. (C) 2016 Elsevier Ltd. All rights reserved.