The reactions of citric acid (C 6 H 8 O 7 ) H 4 cit) with various divalent transition metals (Cd II , Zn II , Cu II , and Co II ) in acid solution or under hydrothermal conditions (pH ) 1-4) have resulted in the isolation of five new coordination polymers with versatile multidimensional frameworks. The five metal citrate complexes, namely, [Cd 3 (Hcit) 5), have been characterized by elemental analysis, FT-IR spectra, thermal analysis, and single-crystal X-ray diffraction studies. While complex 1 was obtained by evaporation of an EtOH-H 2 O solution of the reaction mixture, complexes 2-5 were all prepared under hydrothermal conditions. The crystal structures of the five complexes are remarkably distinct from each other because of the different synthetic conditions or coordination nature of the metal ions. Complex 1 features a 2D multilayered framework which contains an infinite 1D ladder-like structure. Complexes 2 and 3 are almost isostructural, and both exhibit 2D rhombus-grid frameworks. The copper(II) citrate complex 4 displays a new alkyloxylbridging coordination mode, different from other divalent metal citrate complexes. Consequently, the complex forms a 3D openframework polymer with large void channels. Complex 5 crystallizes in a chiral space group and forms a 1D infinite helical chain along a 2 1 axis. The thermal behaviors of the five coordination complexes have been investigated and discussed correlated with the crystal structures in detail. Particularly, the open-framework structure of 4 is responsible for the reversible water desorptionadsorption process.