Nanostructured NiS2 has attracted interest due to its wide applications and special properties. Synthesis of a pure phase NiS2 in a single step has been a challenge. In this work, a new method for direct synthesis of uniform NiS2/SiO2 sub microspheres has been developed by ultrasonic spray pyrolysis. Colloidal silica was used as a sacrificial template to create the porous structure. After silica removal, hollow, porous NiS2 nano spheres were obtained. The product was characterized by using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), transmission electron microscopy and N-2 adsorption/desorption isotherm. XRD confirmed the formation of single phase pyrite NiS2. It was found that the porous spherical NiS2 has a surface area of ca. 300 m(2) g(-1). The HDS catalytic activity of NiS2 was evaluated using a model compound, dibenzothiophene (DBT). It showed a first order reaction rate constant of 1.51 x 10(-4) s(-1) g cata(-1) at 320 degrees C for HDS of DBT, which is significantly promising for further exploration. (C) 2012 Published by Elsevier B.V.