Organic nonlinear optical l-phenylalanine d-mandelic acid (LPDMA) single crystals have been harvested adopting slow solvent evaporation solution growth technique (SSEST) with growth period of 15 days. The XRD studies of the crystal confirm the non-centrosymmetric nature of the crystal. The presence of functional groups for the formation of the compound was confirmed by Fourier Transform Infrared (FTIR) analysis. The UV–Visible spectral studies ascertained linear optical quality and estimation of optical parameters. The nonlinear optical property was studied from Kurtz-Perry powder technique and Z-scan technique. The quantum chemical calculations such as HOMO–LUMO and Molecular Electrostatic Potential (MEP) were calculated and presented. In order to find out various mechanical parameters such as Vicker’s hardness number (Hv), Mayer’s index (n), yield strength (σy) and stiffness constant (C11), Vicker’s microhardness tester was utilized. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.