The syntheses and systematic single-crystal X-ray structural characterization of 1 : 1 copper halide ( CuX )/ligand (L) adducts, CuX.L [X= Cl, Br, I; L= 2-vinylpyridine (2-vpy) and 4- vinylpyridine (4-vpy)], are recorded. For X = Cl, Br; L = 2-vpy, the solid state structures are linear polymers, the basic unit of which is an NCuX2CuN dimer , with the fourth coordination site of each copper linked to adjacent units by coordination of the vinyl group. For X= C1, Br; L = 4-vpy, a linear polymeric NCuX/NCuX infinite spine in one dimension is cross-linked from successive copper/ligand groups alternately to either side through the vinyl groups to adjacent spines to give a puckered sheet structure. The iodides for both ligands are one-dimensional 'stair' polymers with non-coordinating vinyl groups.