Peroxo-polytungstic acid (PTA) is used for preparing the amorphous tin peroxo-polytungstate (Sn-PTA), which can under different thermal decomposition conditions (directly in a reducing atmosphere H-2, or first in air then in H-2) produce two kinds of bronzes : a black hexagonal tin tungsten bronze (HTB) Sn0.23WO3 with a=7.4285(5), c=3.800(3) Angstrom and a cubic tin tungsten bronze Sn0.23WO3 with a=3.79743(6) Angstrom. The powder X-ray and electron diffraction studies are in agreement. It was also observed that the redox reactions between tin tungsten bronzes (both phases) and tin tungstates are reversible.