Some thermal and mechanical properties were measured for tin oxide‐matrix compacts which nominally were composed of 99% by weight tin oxide (SnO2) and 1% zinc oxide (ZnO). The sintered compacts were similar in strength to high–fire mullite porcelains, had superior resistance to thermal shock, and had high thermal conductivity. The tin oxide body might be expected to give good service under conditions of severe thermal shock and in an oxidizing atmosphere at temperatures up to 150