The crystal structure of the title compound, [Cu(en)(2)][K-Co(CN)(6)]}(n) (en is ethylenediamine, C2H8N2), reveals a novel three-dimensional porous framework in which [Cu(en)(2)](2+) acts as a template and K+ as a connecting unit. The Cu atom lies on an inversion centre and the Co and K atoms are on twofold axes.