This book initiates based on the idea that breakthroughs in nanotechnology require a firm grounding in the principles of nanochemistry. Nanotechnology and nanoscience broadly deals with science and technology of materials on the atomic and molecular scale, normally 1 to 100 nanometers. Metal nanoparticles, of either simple or composite nature, play an important and unique physical and chemical properties and represent an increasingly important material in the development of novel nano devices which can be used in numerous physical, biological, biomedical and pharmaceutical applications. Taking into account of the diverse applications of nanoparticles in various fields, the nanoparticles of silver, copper and zinc was synthesized by the chemical reduction methods. Their characterization and antibacterial study was also done. The result of antibacterial studies revealed that the synthesized metal nanoparticles may be promising candidate for wide range of bio-medical applications including tissue engineering, wound dressing, drug delivery and cancer diagnosis.