Chlorine trioxide, Cl2O6, reacts with Au metal, AuCl3, or HAuCl4.nH(2)O to yield the well-defined chloryl salt, ClO2.Au(ClO4)(4). The crystal and molecular structure of ClO2Au(CIO4)(4) was solved by a Rietveld analysis of powder X-ray diffraction data. The salt crystallizes in a monoclinic cell, space group C2/c, with cell parameters a = 15.074(5), b = 5.2944(2), and c = 22.2020(2) Angstrom and beta = 128.325(2). The structure displays discrete ClO2+ ions lying in channels formed by Au(CIO4)(4)(-) stacks. Au is located in a distorted square planar environment: Au-O = 1.87 and 2.06 Angstrom. [ClO4] groups are monodentate with ClOb = 1.53 and ClOt = 1.39 Angstrom (mean distances; O-b, oxygen bonded to Au; O-t, free terminal oxygen). A full vibrational study of the Au(ClO4)(4)(-) anion is supported by DFT calculations.