Two new coordination polymers, {[Co(CH3-ip)(1,4-bib)]· 2H2O} n (1) and {[Co(CH3O-ip)(1,6-bih)]} n (2) (CH3-H2ip = 5-methylisophthalic acid, CH3O-H2ip = 5-methoxyisophthalic acid, 1,4-bib = 1, 4-bis(imidazol-1-yl)butane, 1,6-bih = 1,6-bis(imidazol-1-yl)hexane), have been obtained under hydrothermal conditions. Complexes 1 and 2 were determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis and IR spectroscopy. Complex 1 shows a two-dimensional (2D) corrugated layer containing left and right-handed helical chains. Compound 2 exhibits a 2-fold parallel interpenetrated 2D → 2D net. Furthermore, thermogravimetric properties of 1 and 2 were also investigated. Supplemental materials are available for this article. Go to the publisher's online edition of Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry to view the supplemental file.