The preparation and purification of cadmium mercury thiocyanate, CdHg(SCN)(4) (CMTC) are described. The identity of the synthesized compound was characterized by Raman, infrared and X-ray powder diffraction spectra. The thermal stability and thermal decomposition of CMTC crystals were investigated by means of thermogravimetric analysis and differential scanning calorimetry. The impurities in the growth solutions and their effects are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.