A novel open-framework cerium sulfate hydrate [Ce-III(SO4)(1.5)(HSO4)(0.5)].0.5H(3)O has been synthesized hydrothermally, and characterized by single-crystal XRD, SEM, SQUID, and elemental analysis. In its structure, the CeO7 polyhedra and SO4 tetrahedra are connected via corner sharing in a strictly alternate manner to form an open-framework structure with a one-dimensional eight-membered ring channel system along the b axis. Protonated H2O molecules are accommodated in the channels.