In-doped CdO (InxCd1-xO) thin films were prepared by magnetron sputtering and characterized in detail. Results indicated that the electron mobility improves with small amount of In doping (x = 0.012) to CdO, but then decreases with further In addition. It was proposed that the initial increase in mobility is because the oxygen vacancy concentration decreases and the grain size increases, and that the later degradation is due to the increased scattering by the In ions and the decreased grain size. It was also observed that the carrier concentration, while generally increased with the addition of the In donors, decreases with high amount of In doping (x = 0.072). It was proposed that this is because the solubility limit of In in CdO film is reached and excess In ions form non-conducting In-oxide clusters. It was observed that the In doping widens the energy band gap of CdO film via the Burnstein-Moss effect and the Vegard's rule. (C) 2018 Elsevier B.V. All rights reserved.