The surface work function of transparent conducting oxides is a critical parameter influencing device efficiency by controlling charge transport across interfaces. In this study, Al-doped CdO films were deposited on glass substrates by rf magnetron sputtering with and without oxygen flow. For Al-doped CdO films deposited with (without) oxygen flow, we measure the high (low) surface work function close to 5.4 (4.6) eV. Our results suggest a method for fabricating Al-doped CdO electrodes with large, tunable work functions that could be relevant in designing electrodes for improving the performance of optoelectronic and electronic devices. (C) 2012 Elsevier B.V. All rights reserved.