THz radiation (0.1-10 THz) has unique properties not found in other parts of the electromagnetic spectrum. THz technological applications need high-performance THz imaging and spectroscopy system components such as THz filters, modulators, reflectors. Transparent conducting oxides (TCOs) meet these needs in the THz field. Indium tin oxide (ITO) thin film is one of the most used materials among the TCOs. However, the research on the THz properties of ITO film is currently at an early stage. In this thesis, ITO thin films were deposited on borosilicate (BS), fused silica (FS) and PET substrates using large area magnetron sputtering system. Optical, structural and electrical properties of the ITO films on different substrates were analyzed. Moreover, the effect of electro-annealing in vacuum and air on the properties of ITO films grown on BS and FS substrates were investigated. Furthermore, CW THz imaging system were designed to take THz images of some objects and to analyze THz properties of ITO films grown on FS and PET substrates. Our findings indicate that electrical, structural and optical properties of ITO films can be improved by electro-annealing in air and vacuum. We addressed that electro-annealing in vacuum is more appropriate technique for the applications in industry. We also addressed the importance of oxygen partial pressure and ITO film thickness to adopt them as a transparent electrode in flexible devices. Moreover, our analysis about the THz properties of ITO films on FS and PET substrates showed that fabricated ITO films have potential application in THz field such as THz filters, modulators and reflectors.