In the title compound, C2H5NO2·C8H6O4, the glycine molecule exists as a zwitterion (2-azaniumylethanate) with a positively charged amino group and a negatively charged carboxylate group. In the crystal, N - H⋯O and O - H⋯O hydrogen bonds link the components into layers parallel to the ab plane. The central part of each layer is composed of hydrogen-bonded glycine zwitterions, while phthalic acid molecules interact with the zwitterions in such a way that benzene rings protrude up and down from the layer.
Balakrishnan, T., Ramamurthi, K., & Thamotharan, S. (2013). Glycine-phthalic acid (1/1). Acta Crystallographica Section E: Structure Reports Online, 69(1). https://doi.org/10.1107/S160053681204977X