The X-ray diffraction study of dipyridiniomethane trans-dichlorotetrafluoroosmate(IV) hydrate [or N,N-methyl-enedipyridinium dichlorotetrafluoroosmate(IV) hydrate] at room temperature revealed the complete ordering of the complex anions, i.e. trans-[OsF4Cl2](2-), into AB-type salts with the doubly charged dipyridiniomethane cation [(C5H5N)(2)CH2](2+). A water molecule is linked to the F atoms by hydrogen bridges, resulting in the formation of chains. Hydrogen-bridged F atoms show Os-F distances of 1.938 (3) and 1.944 (3) Angstrom compared with non-bridged F atoms of the anion exhibiting Os-F distances of 1.924 (3) and 1.938 (3) Angstrom. The Os-Cl bond lengths are 2.341 (2) and 2.334 (2) Angstrom.