Nitro Compound, an organic compound that contains one or more nitro groups. (A nitro group consists of three atoms—one of nitrogen and two of oxygen—that act as one.) Nitro compounds may be liquids or solids. They are not usually found in nature. They are prepared commercially by nitration of organic compounds. Nitration is the process in which the hydrogen or other chemical elements linked to a carbon atom are replaced by nitro groups. Nitro compounds are commonly produced by treating a hydrocarbon with nitric acid, usually in combination with sulfuric acid. Nitro compounds are classified according to structure—aliphatic and aromatic.

In aliphatic nitro compounds, also called nitroparaffins, the molecules contain carbon atoms that are joined to form straight or branched chains. These compounds are colorless liquids with relatively high boiling points. They are used as industrial solvents for waxes and dyes and in the manufacture of organic chemicals. The most commonly produced aliphatic nitro compounds are nitromethane, nitroethane, and nitropropane.

In aromatic nitro compounds the molecules contain benzene rings—six carbon atoms joined in a ring characteristic of benzene. Most of these compounds are solids, and usually either colorless or yellow. Aromatic nitro compounds are used as explosives and in manufacturing drugs, dyes, rubber, and photographic chemicals. Nitrobenzene and trinitrotoluene (TNT) are aromatic nitro compounds.