A single crystal of size 5 x 5 x 2 mm(3) of the organic nonlinear optical salt DSTMS (4-N,N-dimethylamino-4'-N'-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate) was grown from solution with seed applied, where growth conditions were optimized. The crystal morphology and growth habit of DSTMS in the presence of seed crystal have been investigated and discussed in the paper. Powder XRD, DSC, TG, FTIR, and transmission and Raman spectroscopies have been applied to characterize the crystallographic structure, and optical and thermal properties of DSTMS. Based on the spectral data, the mechanisms of pronounced nonlinear optical properties of DSTMS are found to be correlated to its bonds in both cation and anion. (C) 2011 Elsevier B.V. All rights reserved.