The copper(I) complex [Cu2L22][ClO4]2·H2O [L2= 2,6-di(2′-methoxyethyliminomethyl)pyridine] has been prepared by reaction of [Cu(MeCN)4][ClO4] with the open-chain Schiff base ‘N3O2’ ligand L2 derived from the condensation of one molecule of 2,6-diformylpyridine with two molecules of 1-amino-2-methoxyethane. Crystals of [Cu2L22][ClO4]2·H2O are monoclinic with a= 20.221 (8), b= 16.239(7), c= 11.345(8)Å, β= 102.2(1)°, Z= 4, and space group P21/n. In the dimeric cation the two copper atoms are directly linked by a Cu–Cu bond of length 2.626(1)Å. In contrast to other metal complexes of pyridyldi-imine ligands the inequivalent copper atoms in the present structure are not bonded to all three nitrogen atoms of the same trimethine group and, moreover, all four imine groups are severely twisted out-of-plane with respect to their respective pyridine rings. Each copper atom is strongly bonded to two imino-nitrogen atoms, one from each ligand molecule. Cu(1) is also weakly bound to two ether oxygens, one from each ligand. The remaining two ether oxygen atoms are not co-ordinated. An unusual feature of the structure is that the pyridine nitrogen atoms appear to act as (asymmetric) bridges between the metal centres [Cu(1)–N, 2.693(6), 2.676(6)Å; Cu(2)–N, 2.237(6), 2.204(6)Å]. I.r. and 1H n.m.r. spectra in CD3CN of the free ligand and complex are compared. Evidence from electronic spectra suggests that the integrity of the dimeric unit is largely retained in solution.