The isotypic compounds Na2(H2O)24[M2(C6H2O4)3] (M = Mn2+, Cd2+) form infinite net-like layers. The transition metal ion is coordinated octahedrally. The dianion of 2,5-dihydroxy-1.4- benzoquinone, consisting of two allyl systems interlinked by two long C-C distances (152-153 pm), acts as a chelating ligand. Adjacent layers are connected by hydrogen bonds. The stacking sequence of these layers, ···AAA···, leads to channels, which are filled by hydrated Na+ ions. The Na+ ions are coordinated in a distorted octahedral fashion, with neighbouring octahedra sharing common faces.