Single crystal growth of anhydrous citric acid (ACA) crystal from slow evaporation technique is reported. It crystallizes in monoclinic system with P21/a space group. Its transmission bandwidth extends from 200 nm to 1100 nm. The different functional band frequencies associated with the crystal, were found out from FTIR and FT Raman spectroscopic analyses. The molecular structure was established by NMR studies. It is thermally stable upto 162 °C. The third order nonlinear optical (NLO) susceptibility χ3 is found to be 1.77 × 10−7 esu and it is better than some reported crystals. © 2019 Elsevier GmbH