Wurtzite-8H nanoporous ZnS spheres assembled from crystallites, were synthesized via a "green" wet chemical route. A possible formation mechanism for the growth process of the ZnS spheres has been proposed based on experimental observations. The prepared catalysts are characterized by transmission electron microscopy, high-resolution transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N-2 adsorption-desorption isotherms, elemental analysis, and UV-vis absorption spectroscopy. The catalyst showed high and stable photocatalytic activity for the degradation of persistent toxic organic pollutants, as demonstrated with azo dye X-3B (X-3B), trichloroacetate (TCA) and phenol under both visible (>420 nm) and UV light irradiation. The experimental results demonstrate that the photocatalytic activity of ZnS spheres is 3.3 and 9 times higher than that of Degussa P25 and commercial ZnS, respectively. The production of (OH)-O-center dot radicals on the ZnS surface was detected by the photoluminescence (PL) technique using coumarin as a probe molecule, which suggests that (OH)-O-center dot radicals are the dominant photo-oxidant in the photocatalytic reaction. More importantly, this synthesis method can be economical for a scale-up process, and may also be applicable to the preparation of additional II-VI semiconductors for catalysis and other applications. (C) 2011 Elsevier B.V. All rights reserved.