Synthesis of nanoparticles can be performed by using different macro to microorganisms such as plants, bacteria, fungi, sea weeds and microalgae. Plant consists of number of natural products like alkaloids, flavonoids, saponins, steroids, tannins and other nutritional compounds. Modern scientific studies have been revealed that the plant extract plays an important role for the preparation of nanomaterials without any hazardous effect. The synthesis of metallic nanoparticle with plant extract is inexpensive, single step and eco-friendly. Cadmium Sulphide Nanoparticles (CdS NPs) were prepared from CdCl2 and Na2S solutions using Artabotrys hexapetalus leaf extract as capping agent. The nanoparticles obtained were characterized by UV-Visible spectrophotometer, X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM) analysis. The formation and stability of the nanoparticles in the colloidal solution was estimated by using UV-Visible analysis. Average diameter of CdS nanoparticles was calculated by using Scherrer equation from the XRD analysis and the antimicrobial activity was studied by cup plate method. CdS nanoparticles prepared using A. hexapetalus leaf extract as capping agent were exhibited highest antibacterial activity against the test organism Staphylococcus aureus and highest antifungal activity against Aspergillus niger test organism.