Dy-doped CdO films were prepared and post-annealed in hydrogen atmosphere for different durations (15 min, 30 min and 45 min). They were characterised by measuring their structural, electrical, and optical properties. The results indicate that annealing in H2 gas does not change the crystalline CdO structure of the films. The electrical behaviours of Dy-doped CdO films show that they are degenerate semiconductors with bandgap 1.75 eV. The bandgap of the hydrogenated Dy-doped CdO films changes with H2-annealing time following the changing in the carrier concentration. These results were found to be in agreement with the available models for bandgap widening and bandgap narrowing. The Dy-doping of CdO films enhances their electrical conduction. An additional enhancement was obtained with pre-annealing in H2 gas so that the greatest enhancement occurs with annealing for 30 min. when the conductivity increased by about 40% and the free-electrons concentration increased by about 260% relative to the non-hydrogenated CdO:Dy film. From transparent-conducting-oxide point of view, Dy is sufficiently effective for CdO doping especially when including a pre-annealing in H2 atmosphere.