The results of chemical synthesis and optical behavior of silver nanoparticles with sizes ranging from 2–10nm which were obtained by reduction of Ag⁺ are reported. The material morphology was examined by transmission electron microscopy (TEM) and physical properties were studied by photoluminescence in the range of 400–550nm using two different excitation wavelengths (320 and 380 nm). The signature provided by the silver plasmon is readily noticed in the silver nanoparticles. The nonlinear optical properties were obtained using a Z-scan setup and agree with previous results obtained by other methods and preparation of samples. In particular, a positive nonlinear refractive index of 5.0115x10 ⁻¹⁰m²/W was obtained for a broad simple of silver nanoparticles between 2 and 10nm. The agreement between the properties of the thin film simple and the nanoparticles give emphasis to the Z-scan technique for nonlinearity measurements of much more complex metal– dielectric structures.