Using solution-based method, silver quantum clusters of different sizes (Ag-20, Ag-140 and Ag-980) have been synthesized and their first hyper-polarizabilities were measured using hyper-Rayleigh scattering technique. We have shown that nonlinear optical properties of silver quantum cluster are highly dependent on the size of quantum cluster. Time-dependent density functional theory calculations using the Amsterdam Density Functional (ADF) program package are used to evaluate linear and nonlinear optical properties of silver tetrahedral Ag-n (n = 10, 20, 35, 56) clusters. Both theoretical and experimental data have shown that nonlinear as well as linear optical properties are highly dependent on the size of silver quantum cluster. (C) 2011 Elsevier B. V. All rights reserved.