The symmetrical anion [β-GluH]⁻ of β-glutamic acid [β-GluH₂] has been introduced into crystal engineering of metal complexes for the first time. Neutralization of aqueous solutions of β-glutamic acid with zinc oxide or lithium hydroxide affords crystalline samples of zinc bis(hydrogen-β-glutamate) trihydrate and lithium hydrogen-β-glutamate hydrate, respectively. [Zn(β-GluH)₂(H₂O)₃] has a layer structure with corrugated sheets featuring a square-grid pattern of the tetra-coordinated zinc dications and bridging [O₂C–CH₂CH(NH₃)CH₂–CO₂]⁻ anions (in their gauche-conformation). The uniform meshes of the network are based on puckered 32-membered rings. Neighbouring undulated layers are mutually shifted into a space-filling indentation which also generates a network of hydrogen bonds involving the ammonio and carboxylate groups and the intercalated water molecules. [Li(β-GluH)(H₂O)] has a less corrugated layer structure based on a parallelogram-grid of lithium cations which are connected by three bridging [β-GluH]⁻ anions (in their anti-conformation). The water molecule is part of the tetrahedral coordination sphere of the metal atom. The layers represent a mixed-mesh network with pores based on 8- and 32-membered rings. Neighbouring layers are mutually shifted to allow for extensive hydrogen bonding.