A superconducting thallium cuprate oxysulfate of the compositlon Tl0.5Pb0.5Sr4Cu2(SO4)O(y), (P4/mmm, a = 3.85Å, c = 16.6Å) related to the 1293 type cuprate family has been characterized. Infrared spectra show that the sulfate ion is present as a bidentate ligand as expected from the structure.
