O- and O-2-bridged Cu pairs in zeolitic environments are examined using density functional theory with cluster models. Both types of oxocation ([CuOCu](2+) and [CuO2Cu](2+)) are found to be highly stable for conditions likely to exist in Cu-ZSM-5. A variety of geometric isomers with different electronic states and preferred Cu-Cu distances are described. Possible implications for "autoreduction", NO decomposition, and other reactions involving Cu pairs in ZSM-5 are explored.