The composition and properties of the electrochemically formed passive layer on cadmium in alkaline solutions were shown to depend on the nature of the electrolyte cation. In 1 M LiOH beta-Cd(OH)(2) was the only product formed, while in I M NaOH and KOH both beta-Cd(OH)(2) and gamma-Cd(OH)(2) were detected. Ex situ FTIR spectroscopy and grazing angle X-ray diffraction were used to characterise the anodic films formed and the results are interpreted in the concept of surface complexation. The reduction of synthetic samples of CdO, beta-Cd(OH)(2) and gamma-Cd(OH)(2), was investigated at a carbon paste electrode. The results show that the reduction of the pure substances is severely suppressed in carbon paste as compared with metallic cadmium. The impact of these results on battery performance is that for thick oxide layers without direct metal contact the reduction is severely retarded and sufficient time and energy are needed to fully charge the cadmium electrode. It is concluded that the reduction process in the presence of cadmium metal involves are-proportionation mechanism.