Imidazole is an organic compound with the formula (CH)₂N(NH)CH. It is a colourless solid that dissolves in water to give mildly basic solution. In chemistry, it is an aromatic heterocycle, classified as a diazole and as an alkaloid.

Derivatives of imidazole, called imidazoles, a common family heterocycles with sharing the 1,3-C3N2 ring, but varying substituents. This ring system is present in important biological building-blocks, such as histidine, and the related hormone histamine. Many drugs contain an imidazole ring, such as antifungal drugs and nitroimidazole.

Imidazole is a planar 5-membered ring. It exists in two equivalent tautomeric forms, because the proton can be located on either of the two nitrogen atoms. Imidazole is a highly polar compound, as evidenced by a calculated dipole of 3.61D. It is highly soluble in water. The compound is classified as aromatic due to the presence of a sextet of π-electrons, consisting of a pair of electrons from the protonated nitrogen atom and one from each of the remaining four atoms of the ring. Some resonance structures of imidazole are shown below: