Under hydrothermal condition, the reaction of 2,4-dichlorophenoxyacetic acid (2,4-DH) and 1,3-bis(4-pyridyl)propane with MnCl 2 Á2H 2 O gave a novel metal-organic framework (MOF), [Mn(2,4-D) 2 (H 2 O) 2 ] n (1). This complex was characterized by IR, elemental analysis, powder X-ray diffraction, and thermogravimetry analysis. X-Ray single-crystal diffraction shows that the Mn(II) ions are bidendate bridged by carboxyl groups in the syn-anti mode, giving a two-dimensional (2D) network. Temperature-dependent magnetic studies reveal that there are weak antiferromagnetic exchange interactions between the Mn(II) ions transmitted by carboxyl groups.