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Aromatic azo compounds (R = R' = aromatic) are usually stable and have vivid colors such as red, orange, and yellow. Therefore, they are used as dyes, which are called azo dyes. Azobenzene is a typical aromatic azo compound.

Aliphatic azo compounds (R and/or R' = aliphatic) are rather unstable. At an elevated temperature or by irradiation, two carbon-nitrogen (R-N) bonds are cleaved simultaneously with the loss of nitrogen gas to generate carbon-centered radicals. Owing to this process, some aliphatic azo compounds are utilized as radical initiators. Azobisisobutylonitrile (AIBN) is a typical one and is widely used in industrial processes and in laboratory experiments.

Aromatic azo compounds can be synthesized by using an azocoupling reaction, that is, an electrophilic substitution reaction on aromatic rings with diazonium salt s. An oxidation reaction of hydrazine (R-NH-NH-R') also gives an azo compound.

Because of their instability, especially for aliphatic ones, care should be taken with the handling of azo compounds or an explosionAn explosion is a sudden increase in volume and release of energy in a violent manner, usually with the generation of high temperature and the release of gases. An explosion causes pressure waves in the local medium in which it occurs. Explosions are cate may occur.