In the title compound, [Cu(C(6)H(6)N(4))(2)](C(9)H(5)N(4)O)(2), the Cu(2+) ion (site symmetry ) is coordinated by two N,N'-bidentate 2,2'-biimidazole (H(2)biim) ligands, generating a square-planar CuN(4) geometry. The dihedral angle between the aromatic rings in the ligand is 0.70 (9)°. In the polynitrile 1,1,3,3-tetra-cyano-2-eth-oxy-propenide (tcnoet) anion, the C-N, C-C and C-O bond lengths indicate extensive electronic delocalization. An alternative description for the metal-ion geometry is an extremely distorted CuN(6) octa-hedron, with two N-bonded tcnoet anions completing the coordination. In the crystal, the components are linked by N-H⋯N and C-H⋯N inter-actions.