Any one of three isomeric aromatic compounds, C6H4(NH₂)₂, with strong basic properties. 1,2-diaminobenzene is a yellow-brown crystalline solid m.p 4 °C used as a photographic developer and in making dyes.

1,3-diaminobenzene is a colourless crystalline solid, m.p 63 °C, which turns brown on standing in air. It is made by reducing 1,3-dinitrobenzene with iron and hydrochloric acid, and is used for making dyes.

1,4-Diaminobenzene is a white crystalline solid, m.p 147 °C which rapidly darkens on standing in air. It is made by the reduction of 1,4-nitrophenylamine and is used as a photographic developer and hair dye.