Amorphous indium tin oxide (ITO) thin films with reduced to 50 mass% indium oxide content were prepared by direct current (DC) sputtering of ITO target in mixed argon oxygen atmosphere onto glass substrates preheated at 523 K. The films were subsequently heat-treated in air at different temperatures in the range of 523-923 K for 60min. The use of oxygen during deposition resulted in highly transparent (>80%) in visible and infrared ranges of spectra films. It has been found from the electrical measurements that as-deposited films under optimum sputtering conditions at working gas flow rate of Q(Ar)/Q(O-2)= 50 sccm/0.5 sccm showed minimum volume resistivity of about 694 mu Omega cm. As-deposited thin films obtained under the optimum condition showed amorphous structure. Improving of crystallisation has been observed with increasing heat treatment temperature. It has been found that DC sputtered films with decreasing amount of indium oxide have smooth surface in contrast to typical ITO (90 mass% indium oxide). (C) 2017 Elsevier GmbH. All rights reserved.