Thallium(I) oxide
Other names
Thallous oxide
3D model (JSmol)
ECHA InfoCard 100.013.838 Edit this at Wikidata
EC Number
  • 215-220-4
  • InChI=1/O.2Tl/q-2;2*+1
  • O([Tl])[Tl]
Molar mass 424.77 g/mol
Appearance black orthorhombic crystals
Density 10.45 g/cm3
Melting point 596 °C (1,105 °F; 869 K)
Boiling point 1,080 °C (1,980 °F; 1,350 K) (decomposes)
soluble (reacts)
Solubility soluble in alcohol and acid
Rhombohedral, hR18[1]
R-3m, No. 166
Related compounds
Other cations
Thallium(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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Thallium(I) oxide is the inorganic compound of thallium and oxygen with the formula Tl2O in which thallium is in its +1 oxidation state. It is black and produces a basic yellow solution of thallium(I) hydroxide (TlOH) when dissolved in water. It is formed by heating solid TlOH or Tl2CO3 in the absence of air. Thallium oxide is used to make special high refractive index glass. Thallium oxide is a component of several high temperature superconductors. Thallium(I) oxide reacts with acids to make thallium(I) salts.

Tl2O adopts the anti-cadmium iodide structure in the solid state.[1] In this way, the Tl(I) centers are pyramidal and the oxide centers are octahedral.

Thallium(I) oxide, like all thallium compounds, is highly toxic.


Thallium(I) oxide can be produced by decomposition of thallium(I) hydroxide at 100 °C or by heating thallium(III) oxide in the absence of air to 700 °C.[2]


  1. ^ a b Sabrowsky H. (1971). "Zur Darstellung und Kristallstruktur von Tl2O". Zeitschrift für anorganische und allgemeine Chemie. 381 (3): 266. doi:10.1002/zaac.19713810305.
  2. ^ Aldridge, S.; Downs, A. J. (2011). The group 13 metals aluminium, gallium, indium and thallium : chemical patterns and peculiarities. Chichester, West Sussex: Wiley. p. 325. ISBN 978-0-470-97655-5. OCLC 716206078.