It is the ion of tellurous acid, and is chemically related to tellurium dioxide (TeO2), whose mineral appearance also bears the name tellurite.

Tellurites are typically colorless or white salts, which in some ways are comparable to sulfite.

Upon acidification of aqueous solutions of tellurite salts, solid hydrated tellurium dioxide (TeO2) precipitates.

This reaction allows the separation of tellurium from selenium since selenous acid remains soluble at low pH.

Tellurite (TeO₃²⁻) is a highly toxic oxyanion of tellurium with notable biological activity, particularly due to its toxic effects on various organisms, including bacteria, plants, and humans.