Nanostructure ITO thin films have been deposited on well cleaned glass and silicon substrates using dc magnetron sputtering technique. The ITO films are post annealed in air using a normal heater setup in the temperature range 100 - 400 °C. The ITO film annealed at 300°C exhibited optimum transparency and resistivity values for device applications. The thickness of the ITO thin films is determined using DEKTAK stylus profilometer. The sheet resistance and resistivity of the ITO films were determined using four probe technique. Finally, the optimized nanostructure ITO layers are incorporated on silicon solar cells and the efficiency of the solar cell are found to be in the range 12-14%. Other solar cell parameters such as fill factor(FF), open circuit voltage(Voc),Short circuit current(Isc), series resistance(Rs) and shunt resistance(Rsh) have been determined. The effect of ITO film thickness on silicon solar cells is also observed.