2-[(2-Hy-droxy-eth-yl)aza-nium-yl]ethanaminium oxalate monohydrate.

In the title hydrated mol-ecular salt, C(4)H(14)N(2)O(2+)·C(2)O(4) (2-)·H(2)O, the oxalate dianion is almost planar (r.m.s. deviation = 0.020†à ). In the crystal, the components are linked by N-H⋯O(water), N-H⋯O(oxalate) O-H(ammonium)⋯O(oxalate), O-H(water)⋯O(oxalate) and O-H(water)⋯O(ammonium) hydrogen bonds, thereby forming a complex three-dimensional packing motif.