(S)-1-Hydroxy-propan-2-aminium (2R,3R)-3-carb-oxy-2,3-dihydroxy-propanoate monohydrate.

The chiral title compound, C(4)H(10)NO(+)·C(4)H(5)O(6) (-)·H(2)O, is a hydrated mol-ecular salt in which the tartaric acid has transferred one proton to the (S)-2-amino-propan-1-ol mol-ecule. The crystal structure is stabilized by a three-dimensional network of N-H⋯O and O-H⋯O hydrogen bonds. The absolute configuration was assigned on the basis of the starting materials.