Thin films of indium tin oxide (ITO) have been deposited on fused quartz substrates by the spray deposition and rf-magnetron sputtering methods and their optical and electrical properties investigated. The junction properties of fabricated ITO/pCdTe and ITO/pInP structures have also been studied and their electrical properties presented. It is established that the deposited ITO films have a lattice constant of 10.14 Angstrom and grow in cubic modifications along the (400) direction. Their transmittance value rises up to between 85% and 90% and extends well beyond the visible range of the spectrum. In the forward direction of the ITO/pCdTe structure, it is suggested that tunnelling dominated processes determine the current flow mechanism. Recombination currents at the interface region and thermionic-emission currents, however, dominate in the ITO/pInP structure at low bias and high bias respectively. The two structures can best be described as heterojunctions.