Hydrazonium(2+) hexafluorosilicate, N2H6SiF6, at room temperature has an orthorhombic(Pbca,Z = 4), pseudotetragonal unit cell (a = 7.605(1) Å,b = 7.586(2) Å,c = 8.543(1) Å). The structure consists of centrosymmetric N2H62+and SiF62−ions arranged in a NaCl-type packing and connected by hydrogen bonds to two-dimensional N2H6–SiF6layers parallel to (001). All H atoms are engaged in hydrogen bonding. Four of the sixbonds to each cation are normal but significantly bent; the other two are trifurcated,, but the out-of-layer component of the trifurcated bond is relatively unimportant. The N2H6SiF6structure is compared in some detail with the structures of other hydrazonium(2+) salts, with particular attention to the N—N bond length, to the "effective" size of the N2H62+ion, and to the tendency of this ion to form bent hydrogen bonds.