NiO and Indium doped (3, 5, 8 and 10 at%) NiO thin films were produced on glass substrates at 400 degrees C by airbrush spraying method using a solution of nickel nitrate hexahydrate. The effect of Indium (In) concentration on the structural, optical and transport properties of NiO thin films was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), spectral transmittance and linear four-probe resistivity. From The X-ray diffraction pattern, it is observed that pure, 3% and 5 at% In doped NiO films have a cubic structure, but 8 and 10 at% doped films have an amorphous structure. Optical measurements show that the band gap energies of the films vary with indium concentrations. Moreover, It has been observed that the doping of NiO films with In increases the electrical resistivity. (C) 2014 Elsevier By. All rights reserved.