Two novel one-dimensional (I-D) cobalt(II) self-assemblies, [Co(pyterpy)(NCS)(2)] (1) and [Co(pyterpy)(SO4)]center dot (CH3OH)(C2H5OH)(H2O) (2) (pyterpy = 4'(4'''-pyridyl)-2,2': 6',2 ''-terpyridine) were synthesized and characterized. Compound I forms a linear chain, and compound 2 forms a zigzag chain. It is thought that the structural differences are caused by binding counter anions as coligands.