Sulfur is a widely used element in different applications such as fertilizers, pharmaceuticals, rubber, fiber industries, bioleaching processes. anti microbial agents, insecticides, and fumigants, etc. Nanosize sulfur particles are useful for pharmaceuticals, modification of carbon nano tubes, and synthesis of nano composites for lithium batteries. In this study we report a surfactant assisted route for the synthesis of sulfur nanoparticles by an acid catalyzed precipitation of sodium thiosulphate. We use both the inorganic and organic acids, and find that organic acid gives lower size sulfur particles. The size of the particles also depends on the reactant concentration and acid to reactant ratio. The effect of different surfactants (TX-100, CTAB, SDBS, and SDS) on particle size shows that the surfactant can significantly reduce the particle size without changing the shape. The size reducing ability is not same for all the surfactants, depending on the type of surfactant. The anionic surfactant SDBS is more effective for obtaining a uniform size in both the acid media. Whereas, the lowest size (30 nm) particles were obtained in a certain reactant concentration range using CTAB surfactant. The objective of this study is to synthesize sulfur nanoparticles in aqueous media and also study the effect of different surfactants on particle size. (C) 2009 Elsevier Inc. All rights reserved.