(S)-Alanine-(S)-2-phen-oxy-propionic acid (1/1).

In the title co-crystal, C(3)H(7)NO(2)·C(9)H(10)O(3), the (S)-alanine mol-ecule exists in the zwitterionic form stabilized by two pairs of N(+)-H⋯O(-) hydrogen bonds and an electrostatic inter-action between the ammonium center and the carboxyl-ate anion, forming a sheet along the ab plane. The carboxyl group of the (S)-2-phen-oxy-propionic acid mol-ecule is connected to the top and bottom of the sheet via N(+)-H⋯O=C and O-H⋯O(-) [R(2) (2)(7) graph set] hydrogen bonds, giving an (S,S)-homochiral layer, in which both methyl groups of (S)-alanine and the phenyl rings of (S)-2-phen-oxy-propionic acid are oriented in the same direction along the b axis.