Silver Oxide (Ag 2 O)Guar gum nanocomposite was fabricated via a simple sonochemical coprecipitation method. The obtained photocatalyst was characterized with various techniques such as Xray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, UVvis diffuse reflectance spectroscopy, photoluminescence spectroscopy, scanning electron microscopy and transmission electron microscopy along with energy dispersion Xray spectroscopy. The findings have demonstrated that Ag 2 O nanoparticles are spherical of 520 nm and were dispersed on the surface of polysaccharide guar gum to form Ag 2 Oguar gum nanocomposite. The assynthesized nanocomposite was enacted as a competent photocatalyst for the reduction of nitrobenzene and oxidation of benzyl alchohol. The conversion efficiency for the reduction of nitrobenzene was 96 % with the addition of sodium borohydride, and the conversion of benzyl alcohol was 98 %. The highly efficient photocatalytic activity was due to the exceedingly dispersed Ag 2 Oguar gum nanocomposite where effective separation rate of energy driven electronhole pairs and stronger light absorption occurs. The possible mechanism of the reactions was implicated in understanding the active species involved in the photocatalytic study.