The title compound, C4H6N2O, displays two predominant hydrogen-bonding inter-actions in the crystal structure. The first is between the unprotonated imidazole N atom of one mol-ecule and the hy-droxy H atom of an adjacent mol-ecule. The second is between the hy-droxy O atom of one mol-ecule and the imidazole N-H group of a corresponding mol-ecule. These inter-actions lead to the formation of a two-dimnensional network parallel to (10-1). C-H⋯O inter-actions also occur.