Aluminium can form an amalgam in solution with mercury. Aluminium amalgam may be prepared by either grinding aluminium pellets or wire in mercury, or by allowing aluminium wire to react with a solution of mercury(II) chloride in water.

This amalgam is used as a chemical reagent to reduce compounds, such as the reduction of imines to amines. The aluminium is the ultimate electron donor, and the mercury serves to mediate the electron transfer.

The reaction and the waste from it contains mercury, so special safety precautions and disposal methods are needed. As an environmentally friendlier alternative, hydrides or other reducing agents can often be used to accomplish the same synthetic result. An alloy of aluminium and gallium was proposed as a method of hydrogen generation, as the gallium renders the aluminium more reactive by preventing it from forming an oxide layer. Mercury has this same effect on aluminium, but also serves additional functions related to electron transfer that make aluminium amalgams useful for some reactions that would not be possible with gallium.