Metallic nanoparticles are traditionally synthesized by wet chemical techniques, where the chemicals used are quite often toxic and flammable. This book deals with a cost effective and environment friendly technique for green synthesis of silver nanoparticles using different species of Ocimum which acts as reducing as well as capping agent. The important ingredients responsible for the formation of silver nanoparticles present in the leaf extract are triterpenes, flavonoids and eugenol.UV¿Vis absorption spectroscopy was used to monitor the formation of silver nanoparticles and Charcterizations were done using, X-ray diffraction analysis, energy-dispersive spectroscopy, scanning electron microscopy, transmission electron microscopy and particle size analyzer.