A metal-rich ternary phosphide, SrPt6P2, with a unique structure type was synthesized at high temperatures. Its crystal structure was determined by single-crystal X-ray diffraction [cubic space group Pa (3) over bar; Z = 4; a = 8.474(2) angstrom, and V = 608.51(2) angstrom(3)]. The structure features a unique three-dimensional anionic (Pt6P2)(2-) network of vertex-shared Pt6P trigonal prisms. The Sr atoms occupy a 12-coordinate (Pt) cage site and form a cubic close-packed (face-centered-cubic) arrangement, and the P atoms formally occupy tetrahedral interstices. The metallic compound becomes superconducting at 0.6 K, as evidenced by magnetic and resistivity measurements.