In this study, we have investigated the potential of bimetallic hollow nanostructures (BHNS) consisting of silver and gold metals for the detection of mercury in an aqueous medium. The BHNS of varying compositions of gold and silver were prepared by galvanic etching of the template silver nanoparticles (AgNPs) using gold(III) salt solution. The BHNS of varying composition were prepared by modulating the molar ratio, of gold to silver, ranging from 0.13 to 2.0, in the reaction mixture. The resultant nanostructures were characterized using UV-Vis spectroscopy and transmission electron microscopy. The absorption maxima of the BHNS batches were found to be increased from 463 ± 9 nm to 611 ± 12 nm as a function of gold to silver molar ratio. An increase in the nanoparticles size was observed from 54 ± 6 (molar ratio = 0.25) to 75 ± 10 (molar ratio = 2.0) with an increase in gold to silver molar ratio. The interaction of different volumes of mercury solution (ranging from 0.1 to 0.4 mL) with all types of BHNS was studied. A considerable change in color of the solution was observed and consequently, a change in the absorbance intensity and a shift in the peak plasmonic wavelength was also noticed. Among the different BHNS batches investigated, the highest change in the intensity and peak wavelength was observed for BHNS0.13, with higher silver and lower gold content. This suggests that the reaction between silver and mercury is more favored compared to that between mercury and gold. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.