© 2016, National Institute of Optoelectronics. All rights reserved.3-mercaptopropionic acid(3-MPA) capped bismuth sulfide nanostructures have been synthesized using an ultrasound-assisted method in an aqueous medium and some of their optical and structural properties have been characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM) and UV-Visible spectroscopy. Reference experiments have also been performed in the absence of capping agent to clearly illustrate the effect of capping mechanism. XRD results show broadening of peaks, suggesting formation of the nanometer sized materials and more smaller sizes in the presence of 3-MPA. UV-Vis absorption spectroscopy results show shifting toward lower wavelength, also confirming the formation of nanostructures with smaller dimension. Surface morphology of the prepared material shows the formation of nearly spherical aggregates of nanoclusters.