[1-(Hydroxy­ethyl­ammonio)propyl]phospho­nate.

The molecule of the title compound, C5H14NO4P, exists as a zwitterion rather than as [1-(hydroxyethyl­amino)propyl]­phospho­nic acid, with the N atom of the amino group protonated and the phospho­nic acid group negatively charged. In the crystal structure, the molecules are linked via extensive hydrogen bonding, forming layers parallel to (100). [ABSTRACT FROM AUTHOR]