In the present study, the photocatalytic decolorization of biebrich scarlet dye (BS) has been investigated in a batch reactor under UV light in slurry mode using different nanophotocatalysts (TiO2, ZnO, CdS and ZnS). ZnO was found to be a better photocatalyst among others for the decolorization of BS. The optimum values of different parameters viz, catalyst dose, pH of the solution and initial concentration of the substrate affecting the decolorization rate of BS were obtained by varying catalyst dose (0.25-1.25 g/L), pH (3-11) and initial concentration (5-100 mg/L). The nano-sized ZnO was synthesized by using precipitation method. The characterization of the prepared ZnO was done with XRD, FT-IR, TGA, SEM and TEM analysis. Then the photodecolorization of the model compound was investigated by using prepared ZnO under optimized conditions. Further the comparative evaluation of the photocatalytic activity of the synthesized ZnO and commercial ZnO powder was made. It was observed that the synthesized nanoparticles exhibited better photocatalytic activity. Experiments were also performed to investigate the reusability of the synthesized ZnO. (C) 2010 Elsevier B.V. All rights reserved.