Metal chalcogenide ZnS nanoparticles have been synthesized using simple capped precipitation method using Potassium pyrosulfate as capping agent. The synthesized nano powder was characterized by X-ray diffraction (XRD), UV–Vis absorption, transmission electron microscopy, infrared spectroscopy, thermogravimetric analysis and fluorescence emission spectroscopy. The XRD pattern exhibits three major peaks at d-values 3.12, 1.904, 1.626 Å belonging to 2θ = 28.60°, 47.76° and 56.60° respectively showing Wurtzite crystal phase of ZnS. UV–Vis spectrum exhibits quantum confinement effect by a very sharp peak around 290 nm remarkably blue shifted compared to its bulk counterpart. The room temperature photoluminescence spectrum of the nanoparticles showed two strong emission bands at 421 and 447 nm. This first blue emission peak at 421 nm is due to sulphur vacancy and other peak at 447 nm belongs to native defect states. © 2015, Springer Science+Business Media New York.