Single crystals are the fundamental building blocks for modern technology. Growth of crystals by gel method is a promising technique for growing single crystals. Nonlinear optical materials (NLO) exhibiting second harmonic generation have been in great demand due to technological importance in the fields of optical communication. Existing organic NLO crystals have poor mechanical and thermal properties and are susceptible to damage during processing even though they have large NLO efficiency. Purely inorganic NLO materials have excellent mechanical and thermal properties. Very little information is available on the studies of various properties of iodate crystals and practically very few attempts have been made to study growth and characterization of iodate crystals. In view of the above, it is decided to grow and study Strontium iodate and Zinc iodate crystals which possess shorter cutoff wavelength, good optical quality, sufficient nonlinear coefficient, transparency in the UV region and excellent thermal stability. Studies on Growth and Thermal, Electrical and Optical properties of Strontium iodate and Zinc iodate have been carried out and results are described in this book.