Two types of TiO2 nanoparticles: i) fluorine-containing TiO2 (F-TiO2) and ii) fluorine-free TiO2 (H-TiO2) nanoparticles, were prepared through a simple, scalable wet-chemical synthesis process, and a comparative study of their photocatalytic properties was conducted. This facile process begins with a one-pot precipitation process at 90 degrees C, followed by heat treatment at 600 degrees C for 1 h in air, resulting in hierarchical, sphere-like, mesoporous structures composed of primary nanoparticles. The microstructural features and crystallographic structures of both types of nanoparticles were systematically investigated by X-ray diffraction, thermogravimetric/differential thermal analysis, X-ray photoelectron spectroscopy, N-2 physical adsorption-desorption, field emission scanning electron microscopy, and transmission electron microscopy analyses. The photocatalytic activities were also evaluated by measuring the degradation of MB. The F-TiO2 nanoparticles showed enhanced photocatalytic activity compared to H-TiO2, which can be attributed to adsorbed fluorine on the surface which leads to various positive effects on the photocatalytic degradation reactions.