An example of a 4,4'-bipyridine (gamma bpy) clathrate in its copper(II) complex has been established. The compound, [Cu(gamma bpy)(H2O)(2)(ClO4)(2)](n).(gamma bpy)(n), crystallizes in the monoclinic space group C2/c with a 16.651(3), b 11.089(2), c 14.360(3) Angstrom, beta 116.45(3)degrees, V 2373.9(8) Angstrom(3). The crystal structure comprises gamma bpy-bridged linear polymeric [Cu(gamma bpy)(H2O)(2)(ClO4)(2)](n) chains, where the copper atom, located on a crystallographic twofold axis, is coordinated in an elongated octahedral environment by two nitrogen atoms of the bridging gamma bpy ligands (Cu-N 1.998(4) Angstrom) and two water molecules (Cu-O 1.968(3) Angstrom) at the equatorial positions, and two perchlorate oxygen atoms at the axial positions (Cu-O 2.414(4) Angstrom). The chains are interconnected by hydrogen bonds between the aqua ligands and the uncoordinated perchlorate oxygen atoms to form two-dimensional layers with cavities each enclosing a gamma bpy molecule. Hydrogen bonding between the aqua ligands and the nitrogen atoms of the solvate gamma bpy molecules further extends the structure into a three-dimensional network in the solid.