The title complex, trans-{mu-2,20-[(1,2-dioxoethane-1,2-diyl)diimino] diethanoato(4-)} bis[diaquacopper(II)] dihydrate, [Cu-2(C6H4N2O6)(H2O)(4)]center dot 2H(2)O, with a three-dimensional framework, displays a square-pyramidal coordination geometry. The structure consists of a neutral centrosymmetric binuclear unit in which the oxamide ligand has a trans geometry, is fully deprotonated and acts in a bis-tridentate fashion.