Ce-doped CdO thin films with different Cd compositions were prepared on glass and Si wafer substrates by a vacuum evaporation technique. The effects of Ce doping on the structural, electrical, and optical properties of the host CdO films were systematically studied. The X-ray diffraction study shows that some of Ce(4+) ions substituted for Cd(2+) and the solubility of Ce in CdO is very limited and may be around similar to 1.3 at%. The cerium doping influences all optoelectrical properties of CdO. The bandgap of Ce-doped CdO suffers narrowing by about 27% with a small (0.5 at%) doping level. The electrical behaviours show that all the prepared Ce-doped CdO films are degenerate semiconductors. Their dc-conductivity, carrier concentration and mobility increase compare with undoped CdO film. The largest mobility of 66.7 cm(2) V(-1) s was observed for 3.8% Ce-doped CdO film. From transparent-conducting-oxide point of view, Ce is sufficiently effective for CdO doping. (C) 2011 Elsevier B.V. All rights reserved.