Nanostructured indium doped CdO thin films were prepared by spray pyrolysis on glass substrate and annealed at 200-400 ?C for 1 hour. The structural, optical, and electrical properties of prepared films were studied using different techniques such as optical transmission, photoluminescence, X-ray diffraction, and Hall measurement. X-ray analysis shows that the In doped CdO films are preferentially orientated along (111) crystallographic directions. Increasing of annealing temperature increases the films packing density and reorient the crystallites along (1 1 1) plane. The optical transmissions of all annealed films decreased with increasing annealing temperature. An increasing in the absorbance and photoluminescence spectra with increasing annealing temperature was denoted in all films. The band gap value of CdO:4%In equals to 2.5 eV and it decreases with annealing temperature and reaches of 2.45 eV for 400°C. The resistivity of annealed films decreased as annealing temperature increased. While high conductivity achieved in the present study is found to be 11.37 ×102 (?.cm)-1 for annealing at 400°C.