Nanoparticles in different field of science have a wide range of utility. They come in different forms. Among these, metal nanoparticles (MNP) have become an emerging tool for diagnostic as well as for therapeutic purposes. Metal nanoparticles are nano-sized particles made up of inorganic metals or their metal oxides. Various methods are available for the preparation/production of metal nanoparticles. In addition to the existing physical and chemical methods, green synthesis is an area that has drawn the attention of researchers in the decade and continues to be a potential area of research. The following review introduces about metal nanoparticles and discusses in details about the plant extract mediated metal nanoparticles synthesis, the principle of metal nanoparticle formation, various process parameters that are important for its synthesis, characterization of metal nanoparticles and the scope for commercialization are elaborated. Metal nanoparticles at research, employing plant extract mediated green synthesis have been extensively reviewed. This review tries to bring into light the feasibility of commercializing the green synthesis by using plant extracts. Keywords: Green synthesis; Plant extract; One-step synthesis; Characterization; Process parameters; Scale-up