The new compound Ta4SI11 has been prepared by direct reaction of the elements at 430 degreesC for 2 weeks in evacuated Pyrex ampules and characterized by single-crystal X-ray diffraction, X-ray photoelectron spectroscopy, magnetic susceptibility measurements, and semiempirical electronic structure calculations. Ta4SI11 crystallizes with orthorhombic symmetry in space group Pmmn; a = 16.135(3) Angstrom, b = 3.813(1) Angstrom, c = 8.131(2) Angstrom, and Z = 1. The disordered structure involves two crystallographically distinct sites for Ta atoms, both of which are 50% occupied as well as a bridging anion site that is 50% S and 50% I. Magnetic susceptibility above 100 K gives mu(eff) = 1.53, mu(B) to suggest one unpaired electron per formula unit. X-ray photoelectron spectroscopy and extended Huckel calculations suggest that the structure consists of Ta-3 triangles and "isolated" Ta. atoms, leading to the formulation (Ta-3)(9+)(Ta4+)(S2-)(I-)(11) and we hypothesize that each Ta-3 is capped by a sulfur atom.