The title complex, [Zn(C5H6O4)(H2O)]n, has a two-dimensional layer structure. The Zn atoms, in a geometry that is closer to trigonal bipyramidal than square pyramidal, are coordinated by two O atoms of a bidentate dimethylmalonate ligand, two O atoms of monodentate dimethylmalonate ligands and one O atom from the aqua ligand. The crystal structure is characterized by the intralayer motif of a hydrogen-bonded network. Neighboring layers are linked together to build up a three-dimensional network via van der Waals forces.