Materials have received immense attention due to their wide applications in various fields of science and technology and can be classified as metals, polymers, ceramics, composites, semiconductors, bio-materials and nanomaterials. Materials science is a broad field and can be considered to be an interdisciplinary area. Included within it are the studies of the structure and properties of any material, the material engineering to suit the needs of specific application.In this book we have presented detail study of the growth, Optimised preparative parameters, structural, optical, and electrical properties of CuI thin films are deposited using modified chemical bath deposition (M-CBD) technique and chemical bath deposition (CBD) techniques. in addition to this the analysis by The various experimental characterization techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), optical absorption, electrical resistivity, thermoemf measurement techniques,PEC Property in dark and after illumination of light are given here.