Piperazine-1,4-diium bis-(perchlorate) dihydrate.

The asymmetric unit of the title compound, C(4)H(12)N(2) (2+)·2ClO(4) (-)·2H(2)O, contains half of a piperazinediium cation, one perchlorate anion and one water mol-ecule. The diprotonated piperazine ring, which is completed by crystallographic inversion symmetry, adopts a chair conformation. In the crystal structure, the cations and anions are linked by inter-molecular N-H⋯O and O-H⋯O hydrogen bonds into a three-dimensional network.