A new organic nonlinear optical single crystal of chalcone derivative, 1-(5-chlorothiophene-2-yl)-3-(4-methoxyphenyl) prop-2-en-1-one (5CT4MP) has been synthesized by slow evaporation technique. The structure of the sample has been determined by CHN analysis, FTIR and H1 NMR. The thermal stability of the grown crystal has been determined from DSC, DSC-TGA. The grown crystal has been characterized for their optical transmission. Second harmonic generation efficiency of the crystals obtained by classical powder technique using Nd:YAG laser is found out to be 1.6 times that of urea. The third order nonlinear optical parameters such as nonlinear optical susceptibility, nonlinear refractive index and nonlinear absorption coefficient have been determined by employing the Z-scan technique. The nonlinearity exhibited by these crystals is used to study the optical limiting behaviour. © 2017, Indian Association for the Cultivation of Science.