Single crystals of N'-[(E)-(4-bromophenyl) (phenyl) methylidene]-4-methylbenzenesulfonohydrazide (4BBTH), having potential applications in nonlinear electro optic field. The structure is elucidated by single crystal X-ray diffraction analysis. The functional groups are identified by FT-IR analysis. The band gap energy is estimated using diffuse reflectance data by the application of Kubelka-Munk algorithm. Third-order nonlinear optical properties of the grown crystal were derived by employing a single beam Z-scan technique. Theoretical calculations were performed using density functional theory (DFT) method. Estimated large first-order molecular hyperpolarizality of 9.79 times of urea, suggests a charge transfer atmosphere facilitating micro level nonlinearity. [GRAPHICS]