TiO2 nanoparticles were prepared by one-step pulsed laser ablation of a titanium target immersed ina poly-(vinylpyrrolidone) solution at room temperature. The products were systematicallycharacterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Ramanspectroscopy and x-ray photoelectron spectroscopy (XPS). The results indicated that the rutileTiO2 nanocrystalline particles were one-step synthesized at room temperature and themean size in diameter is about 50 nm with a narrow size distribution. A probableformation process was proposed on the basis of the microstructure and theinstantaneous plasma plume induced by the laser. Photocatalytic activity wasmonitored by degradation of a methylene blue solution. The as-prepared rutileTiO2 nanoparticles demonstrate a good photocatalytic performance. This work shows thatpulsed laser ablation in liquid media is a good method to synthesize some nanosizedmaterials which are difficult to produce by other conventional methods.