In the title complex, [Mn(C(8)H(4)NO(6))(2)(H(2)O)(4)] x 2H(2)O, cyclic water tetramers forming one-dimensional metal-water chains have been observed. The water clusters are trapped by the co-operative association of coordination interactions and hydrogen bonds. The Mn(II) ion resides on a center of symmetry and is in an octahedral coordination environment comprising two O atoms from two 5-carboxy-2-nitrobenzoate ligands and four O atoms from water molecules.