Cerium(III) methanesulfonate is a white salt, usually found as the dihydrate with the formula Ce(CH3SO3)3·2H2O that precipitates from the neutralisation of cerium(III) carbonate with methanesulfonic acid, as first reported by L.B.

[2][3] The crystals have a monoclinic polymeric structure were each methanesulfonate ion forms bonds with two cerium atoms, which present a coordination number of 8.

[4] The anhydrous salt is formed by water loss at 120 °C.

[5] Cerium(III) methanesulfonate in solution is used as a precursor of electrogenerated cerium(IV), which is a strong oxidant and whose salts can be used in organic synthesis.

[6] The same principle of Ce(IV) electrogeneration is the fundamental reaction in the positive half-cell of the zinc–cerium battery.