Two structurally different 1D cobalt(II) coordination polymers with 4,4'-bipyridine (4,4'-bpy) and 2-chloronicotinate (2-Cl-nic) or 5-bromonicotinate (5-Br-nic), namely {[Co(2-Cl-nic) 2 (4,4'bpy)(H 2 O) 2 ] • 4H 2 O} n (1) and {[Co(4,4'-bpy)(H 2 O) 4 ] [Co(5-Brnic) 4 (H 2 O) 2 ] • 4,4'-bpy • 2H 2 O} n (2), were prepared under the same experimental conditions. The cobalt(II) ions in 1 are bridged by 4,4'-bipyridine ligands into a 1D polymeric chain, each cobalt(II) ion being coordinated with two O-monodentate 2-chloronicotinate ligands and two water molecules as well, while 2 consists of a complex cation {[Co(4,4'-bpy)(H 2 O) 4 ] 2 + } n , in which cobalt(II) ions are bridged by 4,4'-bipyridine ligands into a 1D polymeric chain, and a complex anion [Co(5-Br-nic) 4 (H 2 O) 2 ] 2À , in which cobalt(II) ion is coordinated with four 5-bromonicotinate ligands (two of them being O-monodentate and the other two are Nmonodentate) and two water molecules. DFT calculations revealed a correlation between the halosubstituent (chlorine or bromine) positions in the employed nicotinate ligands and the cobalt(II) coordination environments in the obtained coordination polymers, being responsible for their different structural types.