Chloroxiphite, Pb3CuO2(OH)2Cl2, is monoclinic, space group P21/m, with a = 10·458, b = 5·750, c = 6·693 Å, β = 97·79°, Z = 2. The structure has been refined by the method of least squares from three-dimensional Mo-Kα intensity data to a conventional R value of 0·115. The structure consists of sheets of composition [Pb3 CuO2(OH)2]2−, in themselves made up of the layer sequence Pb-(O, OH, Cu)-Pb, lying parallel to (01). The structure contains eight-fold PbO4Cl4 and seven-fold PbO5Cl2 polyhedra common in other oxychlorides, Pb6 clusters and copper atoms in square planar, Cu(OH)4, coordination.