Coupling reactions involving benzene diazonium chloride with phenol or aniline result in the formation of azo products, such as p-hydroxyazobenzene and p-aminoazobenzene, respectively. These compounds, with extended conjugate systems, are often colored and utilized as dyes.

When diazonium fluoroborate is heated with aqueous sodium nitrite in the presence of copper, the diazonium group is replaced by a -NO₂ group.

Hydrolysis of a diazonium salt occurs when the temperature of the solution rises to 283 K, leading to the formation of phenol.

Mild reducing agents like hypophosphorous acid or ethanol reduce diazonium salts to arenes while being oxidized to phosphorous acid and ethanal, respectively.

Arenediazonium chloride, when treated with fluoroboric acid, forms arenediazonium fluoroborate, which upon heating decomposes to yield aryl fluoride.