In this study, we introduce indium tin oxide (ITO) thin films grown by using low-frequency (60 Hz) magnetron sputtering method. Characteristics of the ITO thin films deposited on polyethersulfone (PES) substrates are investigated. Experiments were carried out as a function of deposition time and substrate temperature. ITO thin films on PES substrate revealed amorphous structure. The optical transmittance, the sheet resistance and the resistivity of the films decreased with the increasing deposition time. The sheet resistance and the roughness of the films increased with the increasing substrate temperature. Roughness values of ITO films on PES substrate deposited at various substrate temperatures are Ra (< 2 nm), Rms (< 3 nm) and Rp-v (< 10 nm). The experimental results confirm that the films with good qualities in surface morphology, transmittance and electrical conduction can be grown by a low-frequency magnetron sputtering method.