Three new organic–inorganic coordination polymers, each adopting a different structural motif, were obtained from the CdI2/pyrazinecarboxylic acid system. Syntheses and X-ray structural determinations are presented. The reaction between CdI2 and 2-pyrazinecarboxylic acid (abbreviated pyzcaH) afforded a one-dimensional chain-like structure, [CdI2(PyzcaH)(H2O)]n (1). When 2-pyrazinecarboxylic acid was replaced by Cu(2-pyrazinecarboxylate)2, the reaction yielded a two-dimensional framework polymer, [CdI(Pyzca)(H2O)]n (2). The reaction of CdI2 and 2-methylpyrazine-5-carboxylic acid (abbreviated MePyzcaH) resulted in the formation of a different coordination polymer, [CdI(MePyzca)(H2O)1.5]n (3), which adopts a one-dimensional chain structure. These new coordination polymers all assemble into three-dimensional structures via networks of hydrogen bonds.