Silver (Ag), gold (Au), and alloy nanoparticles synthesized chemically and Au-Ag core-shell sonochemically produced nanoparticles were investigated for their potential applications in solar cells, biology, transistors, and light-emitting diodes (LEDs). The alloy or core-shell structure can be useful for creating new particles that have the properties of both the core material and the shell material. The Au, Ag, and Au-Ag nanoparticles were characterized optically and structurally by using ultraviolet-visible (UV-Vis) spectroscopy and high resolution transmission electron microscope (HRTEM), respectively. A novel sonochemical approach was used in contrast to the chemical alloy method. The sonochemical approach was used with varying parameters to determine the optimal synthesis parameters for precise control of particle size, geometry, and electrical properties. It was determined that a longer duration of sonication decreased the particle size of the Au-Ag nanoparticles and that the core-shell particles exhibited absorption wavelengths similar to Au nanoparticles, suggesting that Au composes the core of the nanoparticle, but the Ag did not create a shell structure as hoped.