The crystal structure of title salt, C22H46N42+·2NO3−·2H2O, has been determined using synchrotron radiation at 220 K. The structure determination reveals that protonation has occurred at diagonally opposite amine N atoms. The asymmetric unit contains half a centrosymmetric dication, one nitrate anion and one water molecule. The molecular dication, C22H46N42+, together with the nitrate anion and hydrate water molecule are involved in an extensive range of hydrogen bonds. The molecule is stabilized, as is the conformation of the dication, by forming intermolecular N—H⋯O, O—H⋯O, together with intramolecular N—H⋯N hydrogen bonds. [ABSTRACT FROM AUTHOR]