The synthesis and characterization of organic nonlinear optical active (NLO) single crystal of l-threoninium succinate (LTS) were carried out. LTS crystal was prepared by slow evaporation using deionized water over 82 days. Characterizations included single-crystal X-ray diffraction, UV–Vis–NIR spectroscopy, FT-IR analysis, thermal analysis, second harmonic generation, and surface quality. Third-order nonlinear optical properties were estimated at 532 nm using a semiconductor laser. The nonlinear refractive index (n2) = 2.35 × 10–15 m3/W, absorption coefficient (β) = 1.3057 × 10–8 m/W, and third-order susceptibility (χ3) = 1.0571 × 10−13 esu. The laser damage threshold was 52.7 mJ. © 2020 Elsevier B.V., All rights reserved.