N,N-Dimethylamino-N′-methylstilbazolium p-styrenesulphonate (DSSS), a stilbazolium derivative is synthesized by employing the modified counter anion approach. The growth mechanism of DSSS in the methanol–water solvent system is investigated by using the isothermal evaporation method and defects reveal that a layered growth mechanism is adopted by DSSS. The morphology control of the crystal based on supersaturation is further investigated. Powder XRD analysis confirms that DSSS crystallizes in the monoclinic system with the Cc space group. The diffuse reflectance spectrum proved that DSSS is optically similar to N,N-dimethylamino-N′-methylstilbazolium p-toluenesulphonate (DAST). Important optical properties like the absorption coefficient, refractive index and dielectric constant are investigated in order to identify whether DSSS satisfies the requirements of being a Terahertz generating material. Second harmonic generation is found to be similar to that of DAST.