Indium tin oxide (ITO) thin films were deposited by cesium (Cs)-assisted dc magnetron sputtering in an attempt to achieve a high performance at low temperatures. The films were deposited on SiO2/Si wafer and glass (Eagle 2000) substrates at a substrate temperature of 100 °C with a Cs vapor flow during the deposition process. The ITO thin films deposited in the presence of Cs vapor showed better crystallinity than the control films grown under normal Ar/O2 plasma conditions. The resistivity of the films with the Cs assistance was lower than that of the control films. The lowest resistivity of 6.2×10-4 Ω cm, which is ∼20% lower than that of the control sample, was obtained without any postdeposition thermal annealing. The surface roughness increased slightly when Cs vapor was added. The optical transmittance was ≫80% at wavelengths ranging from 380 to 700 nm.