The structures and characteristic features of the molecular packing patterns of complexes of pyridazines containing heterocyclic substituents and the carborane moiety with 2,3,5,6-tetrachlorohydroquinone (TCHQ) were investigated. It was shown that TCHQ can form supramolecular assemblies with carborane-containing substituted pyridazines. The stoichiometry and three-dimensional structures of these assemblies depend on the substituents in the pyridazine ring and are formed via O-H…N hydrogen bonding between TCHQ and heterocyclic molecules.