mercuric oxide

chemical compound

Also known as: mercury oxide, mercury(II) oxide

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 30, 2026

Quick Summary

Mercuric oxide is an oxide of mercury. Mercury (Hg) is a chemical element, a liquid metal in Group 12 of the periodic table, known since ancient times. It is silvery-white, liquid at room temperature, and has a high density. Mercury and its compounds are highly toxic and require careful handling to prevent absorption through inhalation, ingestion, or skin contact.123

Mercuric oxide (HgO) is a compound where mercury has an oxidation state of +2. It is formed when mercury is heated with oxygen to between 300 and 350 °C (572 to 662 °F). At higher temperatures, it decomposes back into its elements. Mercuric oxide is used to prepare various organic mercury compounds and inorganic mercury salts, and it serves as an electrode in mercury batteries.2

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

3 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

mercury
Principal compounds
Mercury(II) oxide, HgO, provides elemental mercury for the preparation of various organic mercury compounds and certain inorganic mercury salts. This red or yellow crystalline solid is also used as an electrode (mixed with graphite) in zinc-mercuric oxide electric cells and in mercury batteries. Mercury(II) sulfide,…
Read More
Mercury(II) oxide, HgO, provides elemental mercury for the preparation of various organic mercury compounds and certain inorganic mercury salts. This red or yellow crystalline solid is also used as an electrode (mixed with graphite) in zinc-mercuric oxide electric cells and in mercury batteries. Mercury(II) sulfide,…
Read More