Cerium(III) sulfate, also called cerous sulfate, is an inorganic compound with the formula Ce<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>. It is one of the few salts whose solubility in water decreases with rising temperature.
Cerium(III) sulfate (anhydrous) is a hygroscopic white solid, which begins to decompose above 600ðC. It has a monoclinic crystal structure.
Cerium(III) sulfate tetrahydrate is a white solid that releases its water of crystallisation at 220 ðC. It has (like the white octahydrate) a monoclinic crystal structure with the space group P2<sub>1</sub>/c (space group 14). The nonahydrate has a hexagonal crystal structure with the space group P6<sub>3</sub>/m (space group 176). Hydrates of this compound are known with 12, 9, 8, 5, 4 and 2 parts of water of crystallisation.