The photocatalytic performance of a novel Nd-SiO2-TiO2 nanocomposite catalyst prepared by a sol-gel method was examined in the degradation of Rhodamine B (RhB), a notorious organic compound present in dye wastewaters. The prepared samples were characterized by low-temperature N2 adsorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectroscopy (DRS). Fourier-transform infrared (FT-IR) spectroscopic analysis indicated the enhanced chemical bonding of O--Ti and O--Ti--O with introduction of Nd and SiO2 dopant species into TiO2. The Nd-SiO2-TiO2 nanocomposite was found to exhibit a much higher photo- catalytic activity toward the decomposition of RhB under both UV and visible light irradiation as compared to a commercial TiO2 photocatalyst. The photodegradation efficiency of RhB (5 mg/L) was greater than 93% under visible light irradiation after 90 min. Addition of SiO2 was shown to not only inhibit crystal growth and TiO2 anatase-to-rutile phase transformation, but also enhance the adsorption of organic compounds. Nd doping has been suggested for slowing down the radiative recombination of photo-generated electrons and holes in TiO2, extending the photocatalyst light response to the visible region. The synergetic effects between Nd-SiO2 and TiO2 are described; the prepared Nd-SiO2-TiO2 represents a noteworthy contribution to the study of pollutant degradation in dye wastewaters.