Ruthenium dioxide hydrate as an oxygen catalyst: a controversy resolved?

Fully hydrated RuO2.xH2O undergoes mainly anodic corrosion, and demonstrates little catalytic activity toward the oxidation of water, when exposed to Ce4+ in solution; however, mild heat-treatment of the oxide (with an optimum at ca. 140 °C)reverses these characteristics, and so can be used to generate reproducibly an active, and stable oxygen catalyst.