New series of benzohydrazide/benzoic acid derivatives were synthesized (4a-b and 5a-b) and subjected to solid-state characterization by NMR spectroscopic measurements. The molecular and crystal structures of 4a and 5a have also been examined by single-crystal X-ray crystallography were reveal that naphthalene frameworks are close to planarity. Besides, the dihedral angle between the mean plane of the naphthalene ring system and the phenyl ring is 2.26(7) and 78.87(8)° for 4a and 5a, respectively. The molecules are linked through N—H⋯O and C—H⋯O hydrogen bonds, forming chains parallel to the ab plane in benzohydrazide and O—H⋯O contacts in benzoic acid. The sheets are further stacked through C—H⋯π interactions resulting in the formation of a 3D supramolecular network. Hirshfeld surface analysis has also been performed to investigate intermolecular interactions in the solid-state; the most important contributions for the crystal packing are from H⋯H, C⋯H/H⋯C, and O⋯H/H⋯O interactions. Additionally, DFT calculations with the B3LYP/6-311G (d, p) level of the theory have been used to analyze the Mulliken atomic charges, molecular electrostatic potential map, and non-linear optical properties of the compounds were produced using the optimized structures. Moreover, the natural bond orbital analysis is conducted to explore the interactions among different orbital and lone pairs taking place within the compounds. The energy framework calculations suggest that the contacts formed between molecules are largely dispersive.