Mixed-oxide powders of tin and tungsten were made by heating various mixtures of SnO and powders, corresponding to the nominal formula WO 3 with x between 0.5 and 2.0, in an argon atmosphere at 600 ¡C Sn x WO 3`x for 15 hours. The phase was the result of heating of an equi-a-SnWO 4 molar mixture of SnO and powders. In addition to 119Sn Mo ssbauer WO 3 experiments, X-ray di †raction and Raman spectroscopy were used to study the phase structures of the mixed-oxide powders. Mo ssbauer spectra from all samples show a small peak at D0 mm/s from phase(s) like rutile SnO 2 , and a larger peak doublet centred at D3.4 mm/s from the phase, a-SnWO 4 where tin is in the form Sn4`and Sn2`, respectively. Another peak doublet centred at D3.0 mm/s was needed to obtain reasonable Ðts for samples with x P 1.3. This doublet originates from an undocumented phase where tin is also in the divalent form Sn2`. 119Sn Mo ssbauer spectroscopy made it possible to reveal the relative amounts of the two valence states of tin in the mixed-oxide structures. Raman spectroscopy as the other probe for ""localÏÏ structures was insensitive to reveal the changes in the phase structures between di †erent mixed-oxide samples up to x \ 1.72, but an extra peak at D890 cm~1 in the Raman spectrum from the sample with x \ 2.0 indicates also the presence of the undocumented phase.