X-ray absorption spectra at the P and S K-edges are reported for the molecules P2O6Sn (n = 1-4) in the gas phase. The X-ray absorption near edge structure (XANES) region is shown to be very sensitive to be valency of the excited phosphorus atom. P4O6 and (C6H5O)(3)PS are used as reference compounds corresponding to the different chemical environments of the phosphorus in the investigated phosphorus oxide sulfides. The XANES spectra of the phosphorus oxide sulfides can be represented by a superposition of the P4O6 and (C6H5O)(3) PS spectra. Using XANES as a fingerprint method, the single lines in the XANES region are assigned to molecular fragments. The results are compared with MS X alpha calculations of the PO3S cluster, which is assumed to contain all the interactions that are relevant for the P(V) portion in the molecules.