The UV-Vis spectroscopy and nonlinear-optical properties of new trans-dichloropalladium(II) complex of 7-azaindole have been investigated using computational chemistry and experimental method. Optical properties were executed using UV-Vis spectroscopy in the spectral range (200-800) nm. The TD-DFT/B3LYP functional method with LanL2DZ basis set for palladium atom and 6-311G++(d,p) for remaining atoms were used to extract the electronic absorption spectra. For nonlinear-optical properties calculation, second-order hyperpolarizabilities (gamma), we used the time-dependent Hartree-Fock (TDHF) level of theory with LanL2DZ and 6-31G(d,p) functional for appropriate atoms. In this work, we studied the influence of the metal cations complexation on the possibility of modulating NLO properties at the molecular level. The calculated results are in good agreement with the experimental values.