We report a facile synthesis of silver nanoparticles (AgNPs) by using a new reducing agent, pretreated N-methyl-pyrrolidone (NMP*). The resulting AgNPs are characterized by using UV-vis, TEM, and X-ray spectroscopy. These AgNPs exhibit strong surface enhanced Raman scattering response on addition of 4-mercaptobenzoic acid. A possible redox mechanism involving silver ion and NMP* was proposed. The oxidized species resulting from thermally treated NMP/O(2) were analyzed by nuclear magnetic resonance and gas chromatography techniques, and it was determined that 5-hydroxy-N-methyl-2-pyrrolidone played the role of reducing agent. The facile synthesis of functional metal nanoparticles via an environmentally friendly procedure with control in particle size, and understanding of the reaction mechanisms pave the ways to further developing metal nanoparticles for chemical and biological detections.