2-Amino-3-carb-oxy-pyrazin-1-ium perchlorate bis-(2-amino-pyrazin-1-ium-3-carboxyl-ate) monohydrate.

The asymmetric unit of the title compound, C(5)H(6)N(3)O(2) (+)·ClO(4) (-)·2C(5)H(5)N(3)O(2)·H(2)O, comprises two symmetry-independent zwitterions, one cation, one perchlorate anion and one water mol-ecule. In the crystal, the three different types of organic entities are linked by N-H⋯O and N-H⋯N hydrogen bonds, forming undulating sheets parallel to (1-10). These sheets are in turn connected by O-H⋯N and O-H⋯O hydrogen bonds involving perchlorate anions and water mol-ecules, forming a three-dimensional network. Intra-molecular N-H⋯O and weak inter-molecular C-H⋯O hydrogen bonds are also present.