In this paper, the degradation of Congo red (CR) as a dye was investigated by a new synthetic photocatalyst. The synthesis was done through the intercalation of CdS in the layers of titanate (K2Ti4O9) by the assistance of ultrasound. The photocatalyst was prepared via ion-exchange reaction and sulfuration processes in the presence of ultrasonic irradiation. The samples were characterized by the field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet-visible spectra (UV-Vis), and Fourier transform infrared spectroscopy (FTIR). The deposition of CdS nanoparticles on the surface and between the spaces of titanate layers led to the shift of absorption edge of titanate to the visible light region. The photocatalytic degradation mechanism of CR has been evaluated through the addition of some scavengers to the solution. In addition, the stability and reusability of the catalyst were examined in this work too. (C) 2015 Elsevier Inc. All rights reserved.