A molecular salt with a bulky cation and anion, (H(2)bipip)(H)(2)[Fe(CN)(6)] (1) (H(2)bipip(2+): 4,4'-bipiperidine-1,1'-diium), has been prepared. The salt comprises protons (H+) as counter cations. Single-crystal X-ray structure analysis revealed that the proton is trapped between two cyanido ligands of [Fe(CN)(6)](4-)anions, forming a very short H center dot center dot center dot H+center dot center dot center dot N hydrogen bond.