[en] The thermodynamic immunity of copper in ultrapure water without dissolved oxygen has been under review since it was suggested that copper, in contradiction to classic thermodynamics, does in fact corrode in this environment. Experiments by Swedish researchers have shown that hydrogen seems to be generated during exposure of copper in ultrapure water without dissolved oxygen. To explain the results it has been proposed that the thermodynamic stability of copper is influenced by a previously unknown and uncharacterized metastable copper(I) hydroxide phase. The existence of this phase would make corrosion of copper in ultrapure water without dissolved oxygen plausible. However, previous attempts to verify these results using different methods have so far not been successful. Experiments have now been performed at Studsvik to further study if hydrogen gas can be evolved via a reaction of copper and ultrapure water without dissolved oxygen. The experiments have been performed in a two chamber system separated by a thin palladium foil which allows for hydrogen to pass through it. Copper and water is placed in one of the chambers and the other is evacuated. A pressure increase on the other side of the palladium membrane is attributed to corrosion of copper. The same techniques were used by the Swedish researchers mentioned above. Three experiments were performed. In two of the tests copper was exposed in ultrapure water without dissolved oxygen and in the third platinum was used as a reference experiment without the possibility for hydrogen evolution. The results obtained showed that hydrogen gas was evolved during the exposure of copper in ultrapure water without dissolved oxygen, but not during the reference experiment with platinum exposed in the same experimental setup and under the same experimental conditions. The total amount of hydrogen detected after the test is lower than what would be possible with respect to the copper amounts found in the test solutions after the experiments. The same observation was made in previous experiments mentioned above. In addition in this work the test solutions were shown to contain unexpected amounts of metals. However, the gas and the test solution analyses and their interpretations are complicated and were originally outside the scope of this work