C101 Oxygen Free Copper is extremely pure copper with very little oxygen content. With a typical oxygen content of less than 0.0005% and a typical copper grade of 99.99%, C101 Oxygen Free Copper is the highest-grade copper available, and the material properties closely resemble that of elemental copper. The target purity is so high that silver is removed as an impurity.

As an ultra-high purity copper product, C101 Oxygen Free Copper has very good electrical and thermal conductivity, has good machinability, and is highly ductile. By reducing the oxygen content to less than 0.0005% these properties are more exaggerated than standard copper products and as such find a variety of highly specialized industrial applications.