Single crystal of manganese mercury thiocyanate (MMTC) and cadmium mercury thiocyanate (CMTC) were grown by slow evaporation technique. The conditions for the growth were optimized. The cell parameters of the grown crystals were confirmed by using single crystal Xray Diffraction. The grown crystals have high NLO efficiency compared to KDP and urea. The optical properties were studied by using UV-Vis spectroscopy. The optical band gap energy values of MMTC and CMTC crystals were reported. The measurement of complex impedance response to small ac signals was carried out in the frequency range of 20 Hz to 1MHz at different temperatures. The activation energy has been calculated using Arrhenius plot as a function of temperature.
