Abstract The N-oxide or 1-hydroxy forms of four solid 1-hydroxy-5-(4-methyl-2-nitroimidazol-2-yl)-4-phenyl-2-(X-phenyl)-imidazole derivatives, 6, have been studied by X-ray crystallography. Compounds, (6: X=4-Br) and (6: X=2-O2N), both recrystallized from EtOH, and (6: X=4-F), recrystallized from EtOCH2CH2OH, were isolated in the 1-hydroxyimidazole form. In contrast, (6: X=H), recrystallized from EtOCH2CH2OH, was obtained in the imidazole N-oxide form. Two independent molecules, Mol A and Mol B, rotamers, are present in the asymmetric unit of the imidazole N-oxide compound, (6: X=H) and are linked into chains of alternating compounds, mainly by N–H···O hydrogen bonds, but also by N–H···N and C–H···O hydrogen bonds and π···π interactions. These chains are linked by other C–H···O and C–H···N hydrogen bonds and π···π interactions into a 3-D arrangement. In the 1-hydroxyimidazole compound, (6: X=2-O2N), classical hydrogen bonds, O1–H1···N3, are the major interactions linking molecules into C(5) chains: weak π···π stacking interactions also link the molecules within the chains. These chains are linked by C–H···O and hydrogen bonds and by N–O···π interactions into a three- dimensional array. The other 1-hydroxyimidazole compounds, (6: X=4-Br) and (6: X=4-F), have similar structures, which differ from that of (6: X=2-O2N). In (6: X=4-Br) and (6: X=4-F), pairs of classical O–H···N hydrogen bonds link molecules into symmetric dimers: these dimers are further stabilized by π···π interactions. Other intermolecular interactions found in both (6: X=4-Br) and (6: X=4-F) are C–H···O hydrogen bond and N–O···π interactions, which link the O–H···N hydrogen bonded dimers into a 3-dimensional array.