Resistively heated strip specimens of Cb-1Zr alloy were exposed at 927 °C in a vacuum chamber at various levels of total pressure in the 10−6-Torr range and oxygen partial pressures in the 10−7-Torr range. Pressure levels were maintained by controlled in-leakage of air. Oxygen reacts rapidly with Cb–1Zr alloy under these conditions and final oxygen content of the specimens was between 4000 and 9000 ppm for exposure times between 200 and 500 h. Oxygen reaction rates (sticking probabilities) were calculated both from the total oxygen pickup and from the vacuum chamber gas analyses. Good agreement was obtained between the two methods. Oxygen sticking probabilities were found to depend on whether or not the specimens were annealed immediately before the test exposure. These results indicate that a normally undetectable oxide film exists on the Cb–1Zr surface as a result of oxidation by ambient air, and causes the sticking probability to be lower than on the clean metal surface. Sticking probabilities ranged from 0.65 on the clean surface to 0.16 on the surface with the oxide film. Mechanical tests of the contaminated material showed that Cb–1Zr alloy is considerably strengthened by addition of oxygen to an oxygen level of about 6000 ppm, while still maintaining reasonably good room temperature ductility. At higher oxygen levels, the ductility decreases markedly with little additional increase in strength. Welded and annealed Cb–1Zr is considerably more sensitive to oxygen contamination. The weld metal is brittle after addition of 4300 ppm oxygen.