In the title compound, {[(C2H5)3NH] [Cu2(CH3COO)5]·C4H8O} n, the two different CuII atoms are coordinated in a pseudo-square-pyramidal environment by five O atoms from the acetate ligands. Neighbouring pairs of CuII atoms are linked by four basally coordinating bridging acetate ligands as in the crystal structure of copper acetate monohydrate. The fifth, apically coordinating ligand links two of the dicopper tetraacetate paddlewheel-units together, thus building a linear coordination polymer which extends along [101̄]. Each apical acetate ligand is linked by an N - H⋯O hydrogen bond to a triethylammonium cation. Weak C - H⋯O hydrogen bonding interactions also occur.