Aluminium monochloride, or chloridoaluminium is the metal halide with the formula AlCl.

Aluminium monochloride as a molecule is thermodynamically stable at high temperature and low pressure only.

[2] This compound is produced as a step in the Alcan process to smelt aluminium from an aluminium-rich alloy.

When the alloy is placed in a reactor that is heated to 1,300 °C and mixed with aluminium trichloride, a gas of aluminium monochloride is produced.

This molecule has been detected in the interstellar medium, where molecules are so dilute that intermolecular collisions are unimportant.