N-[tris(hydroxymethyl)methyl]glycine(tricine).

The title compound, C(6)H(13)NO(5), adopts a zwitterionic form where the carboxylic acid H atom is transferred to the amino group. The methyl-glycine backbone is planar. The tris(hydroxymethyl)methyl group is rotated as a rigid group around the amino-methyl bond by 22 (1) degrees and the carboxylic acid plane is rotated by 19.76 (12) degrees from the plane of the main skeleton. Apart from their H atoms, the three hydroxymethyl groups adopt a propeller-like conformation around the amino-methyl bond, close to C(3) symmetry.