In this study, indium tin oxide (ITO) films were made from an oxidized target with In2O3 and SnO2 in a weight proportion of 9:1 using the radio frequency magnetron sputtering method. Hydrogen was added to the gas mixture during the preparation of the ITO films. In order to study the effect of hydrogen partial pressure on the structural and optoelectronic properties of the ITO films, we have varied the hydrogen partial pressure in the gas mixture over the range 0–1.6×10-5 Torr and kept the substrate temperature constant at 300 °C during film growth. The x-ray diffraction patterns of ITO films prepared at different hydrogen partial pressures show that the films have (111) and (100) preferred orientations. Hall effect measurements reveal that the addition of hydrogen in the sputtering gas mixture shows an increase in the number of charged carriers in the ITO films. However the carrier mobility did not increase considerably. At optimal conditions, ITO films with resistivity of 2.7×10-4 Ω cm and transparency of over 89% in the visible wavelength region were achieved. © 1999 American Institute of Physics.