The novel compounds M 2+ Zr(SO 4) 3 with M = Mg, Mn, Co, Ni, Zn, and Cd as well as (Fe 3+,2+ ,Zr) 2 (SO 4) 3 were synthesized at mild hydrothermal conditions (Teflon-lined stainless steel vessels, 220 °C) from the mixtures of Zr 2 O 2 (CO 3)(OH) 2 , the respective M 2+ (SO 4)•nH 2 O hydrated salts, H 2 SO 4 and a minor amount of water. Crystals up to several tenths of a mm in size were obtained within a few days and studied at 200 K by single-crystal X-ray diffraction techniques. All these compounds belong to the structure type of monoclinic Fe 2 (SO 4) 3 ; they are either isotypic in space group P2 1 /n (No. 14), Z = 4, i.e. M 2+ Zr(SO 4) 3 with M = Mn, Co, Ni, Zn, and Cd as well as the mixed valence sulfate (Fe 3+,2+ ,Zr) 2 (SO 4) 3 or in the case of MgZr(SO 4) 3 , closely related but with a larger unit cell, in space group Pc and Z = 8. The framework of the monoclinic Fe 2 (SO 4) 3 structure is characterized by two types of isolated Fe 3+ O 6 octahedra, corner-linked with three types of sulfate groups. In the isotypic M 2+ Zr(SO 4) 3 series, the Fe 3+ atom on the Fe(1) position is substituted by Zr 4+ while M 2+ ions occupy the Fe(2) site in the ferric sulfate structure type. Mean cation-oxygen bond lengths (S [4] : 1.462-1.472 Å; Zr [6] : 2.053-2.060 Å as well as M 2+-O distances) are generally rather short, but still within the range reported in literature.