The authors have found a new structural type, related to α-PbO 2, called tri-α-PbO 2. The oxide Fe 2WO 6 is the prototype. It crystallizes in the orthorhombic system with the following cell parameters: a = 4.576 Å, b = 16.766 Å, and c = 4.967Å. The space group is Pbcn. The structure has been determined by X-ray single-crystal methods and refined by least-squares procedures ( R = 0.065). The structure consists of zig-zag chains parallel to the c-axis. Each such chain is built up by MO 6 (M = Fe or W) octahedra-sharing edges. The chains are linked together by corner sharing. There are two types of chains: one containing only iron atoms, the other being an ordered 1-1 arrangement of iron and tungsten atoms.