In the present work, copper nanoparticles have been synthesized by green method, using Syzygium cumini plant leaf extract as reducing agent. The biosynthesized CuNPs were characterized using UV-Vis analysis, X-ray diffraction analysis (XRD) and Transmission Electron Microscopy (TEM) analysis. TEM image shows that the synthesized CuNPs were spherical in shape with a mean diameter of 4.68 nm. The electrochemical activity of copper nanoparticles was studied by cyclic voltammetry. The CuNPs showed excellent catalytic activity in the reductive degradation of indigo carmine and methyl red dye.