Iridium(IV) oxide

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Iridium(IV) oxide
Other names
Iridium dioxide
3D model (JSmol)
ECHA InfoCard 100.031.572
Molar mass 224.22 g/mol
Appearance blue-black solid
Density 11.66 g/cm3
Melting point 1,100 °C (2,010 °F; 1,370 K) decomposes
+224.0·10−6 cm3/mol
Rutile (tetragonal)
Octahedral (Ir); Trigonal (O)
Flash point Non-flammable
Related compounds
Other anions
iridium(IV) fluoride, iridium disulfide
Other cations
rhodium dioxide, osmium dioxide, platinum dioxide
Related compounds
iridium(III) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Iridium(IV) oxide, IrO2, is the only well characterised oxide of iridium. It is a blue black solid. The compound adopts the TiO2, rutile structure, featuring six coordinate iridium and three coordinate oxygen.[1]

It is used with other rare oxides in the coating of anode-electrodes for industrial electrolysis and in microelectrodes for electrophysiology research.[2]

As described by its discoverers, it can be formed by treating green form of iridium trichloride with oxygen at high temperatures:

IrCl3 + O2 → IrO2 + 1.5 Cl2

A hydrated form is also known.[3].


  1. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  2. ^ Cogan, Stuart F. (August 2008). "Neural Stimulation and Recording Electrodes". Annual Review of Biomedical Engineering. 10 (1): 275–309. doi:10.1146/annurev.bioeng.10.061807.160518.
  3. ^ H. L. Grube (1963). "The Platinum Metals". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. NY: Academic Press. p. 1590.