The title compound, C8H9NO3, is the zwitterionic form of d-(−)-4-hydroxyphenylglycine. The plane of the hydroxybenzene ring is inclined at an angle of 88.89 (5)° to the best-fit plane through the five non-H atoms of the aminoacetate substituent. In the crystal, N—H...O and O—H...O hydrogen bonds link adjacent molecules, forming a three-dimensional network. Weak C—H...π interactions are also observed.
