Dichloro-diglycine zinc II (DCDGZ II), a semi-organic nonlinear optical material has been synthesized and single crystals were grown from the aqueous solution up to dimensions 20 × 10 × 3 mm3. The title compound, DCDGZ II (C4H10Cl2N2O4Zn áH2O) crystallizes into monoclinic structure with the space group of C2/c. The unit-cell parameters were found to be a=14.4191(7), b=6.9180(2), c=12.9452(6) ? and Z=4. In the crystal structure, DCDGZ II layer is building up altatingly with layers of water in which the zinc ions lie on a twofold axis. Theoretical calculations for polarizability, which are useful for device fabrication were made using Clausius-Mosotti equation and Penn analysis and the results were compared. Fourier transform infrared (FTIR) spectroscopic studies were performed for the identification of the different functional groups presented in the compound. The UV-vis-NIR absorption spectrum reveals that the lower UV cut-off wavelength is 240 nm. The optical band gap of the crystal was estimated as 2.2 eV. The surface morphology, thermal behaviour, dielectric properties have been studied using SEM, TG/DTA and LCR HITESTER analyzer. The nonlinear optical property of the crystal was also confirmed using Kurtz powder technique.