The structural and nonlinear optical properties of the Schiff base material, (E)-4-fluoro-N′-(pyridin-2-ylmethylene)benzohydrazide monohydrate (FPMBH) were studied. The experimental investigations were performed using Fourier transform infrared (FTIR), ultraviolet (UV) and nuclear magnetic resonance (NMR) spectral techniques. The computational analyses were made by DFT method. A comparison between experimental and theoretical predictions was made and interpreted. The maximum absorption wavelength was found by both experimental and theoretical analyses. The Hirshfeld surface analysis was performed to understand the various molecular interactions. Highest occupied and lowest unoccupied molecular orbitals (HOMO–LUMO) analysis was performed for the title molecule to know about the possible charge transfer taking place within the molecule. Reactivity features were also determined by molecular electrostatic potential (MEP) analysis. The third-order nonlinear optical studies were done by z-scan experiment, and the results were discussed. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.