Many of the bimetallic thiocyanate complexes have been found to exhibit excellent nonlinear optical properties. Single crystals of one such material Cadmium mercury thiocyanate CdHg(SCN)4 have been grown in silica gel using gel technique by the process of diffusion. The grown crystals subjected to single crystal X-ray diffraction study confirms that the crystals belong to tetragonal system. Dielectric studies reveal that the dielectric constant decreases with increase in frequency. Polarizability calculated by Penn analysis is compared with the traditional methods and tabulated. The Second harmonic generation efficiency of the gel grown CMTC crystal has been determined in comparison with Urea.