In the title complex, [Mn(C(9)H(4)N(2)O(4))(H(2)O)(2)](n), the Mn(II) atom is in a distorted octa-hedral coordination completed by one N atom from one 1H-benzimidazole-5,6-dicarboxyl-ate ligand, two O atoms from two different 1H-benzimidazole-5,6-dicarboxyl-ate ligands, and three O atoms from three water mol-ecules. Two bridging water mol-ecules and two bridging carboxyl-ate groups from a 1H-benzimidazole-5,6-dicarboxyl-ate ligand connect two Mn(II) ions into a dimeric structure. In the crystal, extensive inter-molecular O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonding forms a three-dimensional network.