5-Carb-oxy-1,3-bis-(carb-oxy-meth-yl)-4-imidazolinium-4-carboxyl-ate.

The title compound, C(9)H(8)N(2)O(8), was obtained by the reaction of imidazole-4,5-dicarb-oxy-lic acid and 2-chloro-acetic acid. An intra-molecular O-H⋯O hydrogen bond occurs. The crystal packing is stabilized by intermolecular O-H⋯O and C-H⋯O hydrogen bonds, which link mol-ecules into a three-dimensional network.