The reaction of PtI₂ with Bi and BiI at 630 K yields black, lustrous, air insensitive crystals of the subiodide Bi₁₃Pt₃I₇;. The layered crystal structure (triclinic, C1, α = 1581.0(2) pm, b = 912.6(1) pm, c = 2149.6(6) pm, α = 90.03(2)°, β=96.96(2)°, γ = 90.11(1)°, V = 3078.6 · 10⁶ pm³) contains edge-sharing [PtBi_8/2] cubes, which form nets of Kagomé type. Iodine atoms fill the hexagonal-prismatic voids therein. These ²∞[(PtBi_8/2)₃I] layers are alternately separated by layers of iodine atoms or ¹∞[BiI^-₄] zigzag-chains. The marked pseudo-symmetry of the structure favours stacking faults, which cause streaks of diffuse scattering in the diffraction pattern.