The study of semiconductor is the subject of prime importance as far as science and technology is concerned. Electrical conductivity of semiconductor is intermediate to that of conductors and insulators, and is used in almost in all technological devices. Transparent conducting oxides (TCOs) are specific group of semiconductors which show simultaneous transparency and electrical conduction. The best TCO thin film is recognized by its structural, optical and electrical properties which are depends upon various factors like, material, the thin film deposition method, deposition parameters like, temperature, concentration, thickness of films, impurities present in films, structure and nature of thin films.With the technological innovations, new TCO materials are upcoming with better opto-electrical properties that can satisfy the need of the globe. This book presents thin film deposition and characterization techniques, effect of various parameter and doping on CdO thin film deposited by spray pyrolysis method.