Mercurous chloride (Hg2Cl2) is an inorganic compound consisting of two mercury atoms and one chlorine atom. It is a white or yellowish powder or crystal that has a lustrous color but tends to darken in the air. Mercurous chloride is not easily soluble in water, but it is soluble in concentrated hydrochloric acid and ammonia.

Mercurous chloride is a reducing agent that reacts with an oxidizing agent to form mercuric chloride. It is also used as a titrant in analytical chemistry to determine the content of chloride ions and other anions. In addition, mercurous chloride is also used in the pharmaceutical and electroplating industries.