[1] It does occur in nature, although only very rarely, as two polymorphs known as krotite and dmitryivanovite, both from meteorites.

Monocalcium aluminate is formed when the appropriate proportions of calcium carbonate and aluminium oxide are heated together until the mixture melts.

In calcium aluminate cements, it exists as a solid solution in which the amount of minor elements depends upon the bulk composition of the cement.

It reacts rapidly with water, forming the metastable hydrate CaO·Al2O3·10H2O, or a mixture of 2CaO·Al2O3·8H2O, 3CaO·Al2O3·6H2O and Al(OH)3 gel.

These reactions form the first stage of strength development in calcium aluminate cements.