Effect of pH on the stability of aqueous solution and growth kinetics of bis-(dimethylsulfoxide) cadmium mercury thiocyanate has been investigated. The solubility was estimated for the optimized pH value of 3.5. Bulk single crystals were grown from mixed solution of water:dimethylsulfoxide (3:1) by slow cooling and slow evaporation methods under the optimized pH value. The structure and morphology of the grown crystal was confirmed by single crystal X-ray diffraction analysis. Presence of functional groups and the coordination of dimethylsulfoxide to the parent compound of cadmium mercury thiocyanate were confirmed through Fourier transform-infrared spectroscopy and further they were confirmed by laser Raman spectroscopic analysis. Optical transparency of the grown crystal was observed by UV-visible spectroscopy. The thermal stability and thermal decomposition of cadmium mercury thiocyanate (CMTD) single crystals were investigated by means of thermo gravimetric analysis, differential thermal analysis and differential scanning calorimetric analysis. The nonlinear optical efficiency of the grown crystal was estimated by Kurtz powder method. (c) 2008 Elsevier B.V. All rights reserved.