An organic quinolinium derivative crystal 1-ethyl-2-[2-(3,4,5-trimethoxy-phenyl) vinyl]-quinolinium iodide has been synthesized by knoevenagel condensation reaction and the crystals were grown by solution growth method for the first time. The grown crystal structure was confirmed by single crystal X-ray diffraction analysis and it showed that TMQI crystal belong to the triclinic space group P-1. The molecular structure and composition of the crystal was further confirmed by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (FT-NMR) spectroscopic techniques. The thermal stability of the title crystal has been investigated by TG/DSC curves. The linear optical response of the grown crystal has been examined by using UV–Vis-NIR spectral analysis, and the photoluminescence spectrum exhibits strong emission radiation at 558 nm. The chemical etching analysis was carried to reveal the growth pattern of TMQI crystal. Laser induced damage threshold of the title crystal was found to be 1.15 GW/cm2. The third order nonlinear optical property of grown crystal was studied using Z-scan technique and the magnitude of third order nonlinear susceptibility has found to be in the order of 10−3 esu, which is higher than the reported quinolinium derivative crystals. © 2017, Springer Science+Business Media New York.