We report on the preparation of a novel near infrared photocatalyst by combining a low energy band gap semiconductor CdS with an upconversion material NaYF4 Yb Tm Particles of CdS and NaYF4 Yb Tm are pretreated with thioglycolic acid and mercaptoethanol The reaction between these two organic molecules causes the formation of NaYF4 Yb Tm/CdS composite Results from scanning electron microscopy (SEM) transmission electron microscopy (TEM) energy-dispersive X-ray spectroscopy (EDX) and powder X-ray diffraction (XRD) measurements demonstrate that CdS nanoparticles are uniformly assembled on the surface of NaYF4 Yb Tm microrods Energy transfer from NaYF4 Yb Tm to CdS is confirmed by the upconversion and fluorescence decay properties Hydroxyl radicals are generated upon NIR irradiation on the composite material The NIR photocatalytic activity of the NaYF4 Yb Tm/CdS composite is investigated by degrading Rhodamine B and methylene blue A mechanism for NIR-driven photocatalysis is proposed (C) 2010 Elsevier B V All rights reserved