Abstract: High nonresonant second-order hyperpolarizability has been measured for a solution of 3-methyl-4-methoxy-4'-nitrostibene (MMONS) in tetrahydrofuran 1.68 x 10--28 nm2/V2 at a wavelength of 1.06 po The corresponding value of third-order susceptibility for the solid-state is calculated to be The nonlinearoptical response the is less than 50 ps. These results show that MMONS may prove to be one among the hot nolinear optical materials in prospect.