The title complex [Cu(4,4?bpy)(H2O)3]SO42H2O (Mr = 405.86) was synthesized under hydrothermal conditions and its crystal structure has been determined by X-ray diffraction. It crystallizes in the hexagonal system, space group P61 with a = 11.1870(4), c = 21.578(1) ? V = 2338.6(2) ?, Dc = 1.729 g/cm3, Z = 6, m(MoKa) = 1.583 mm-1 and F(000) = 1254. The final R and wR are 0.0253 and 0.0416 for 1458 observed reflections with I≥2s(I), respectively. It was revealed that the square pyramidal Cu(II) sites are linked through 4,4?bipyridine groups, forming infinite one-dimensional chains, with the sulfate anions and lattice water molecules occupying the inter-chain positions. During the electrostatic interactions, there exist O…O hydrogen bonds and p-p stacking interactions between the parallel aromatic bipy rings in the structure.