[7] Anhydrous MgCl2 is produced industrially by heating the complex salt named hexamminemagnesium dichloride [Mg(NH3)6]2+(Cl−)2.

[10] The Lewis acidity of magnesium chloride is reflected in its deliquescence, meaning that it attracts moisture from the air to the extent that the solid turns into a liquid.

The production of metallic magnesium at the cathode (reduction reaction) is accompanied by the oxidation of the chloride anions at the anode with release of gaseous chlorine.

Magnesium chloride is one of many substances used for dust control, soil stabilization, and wind erosion mitigation.

[12] When magnesium chloride is applied to roads and bare soil areas, both positive and negative performance issues occur which are related to many application factors.

When highways have dangerous ice buildup, road maintainers apply magnesium chloride to deter ice from bonding to the pavement, allowing snow plows to clear treated roads more efficiently.

For the purpose of preventing ice from forming on pavement, magnesium chloride is applied in three ways: anti-icing, which involves spreading it on roads to prevent snow from sticking and forming; prewetting, which means a liquid formulation of magnesium chloride is sprayed directly onto salt as it is being spread onto roadway pavement, wetting the salt so that it sticks to the road; and pretreating, when magnesium chloride and salt are mixed together before they are loaded onto trucks and spread onto paved roads.

[17] The amount of magnesium chloride is supposed to be controlled when it is used for de-icing as it may cause pollution to the environment.

In Japan it is sold as nigari (にがり, derived from the Japanese word for "bitter"), a white powder produced from seawater after the sodium chloride has been removed, and the water evaporated.

[20] This is due primarily to the chlorine present in magnesium chloride, which can easily reach toxic levels if over-applied or applied too often.

[22] It is used to supply the magnesium necessary to precipitate phosphorus in the form of struvite from agricultural waste[23] as well as human urine.

Carbonates and calcium[clarification needed] are essential for all growth of corals, coralline algae, clams, and invertebrates.

Magnesium can be depleted by mangrove plants and the use of excessive limewater or by going beyond natural calcium, alkalinity, and pH values.

Once inside the plant, chloride moves through the water-conducting system and accumulates at the margins of leaves or needles, where dieback occurs first.