Mercury(II) stearate is a metal-organic compound, a salt of mercury and stearic acid with the chemical formula C
₃₆H
₇₀HgO
₄. The compound is classified as a metallic soap, i.e. a metal derivative of a fatty acid. The compound is highly toxic by inhalation, ingestion, and skin absorption.

An exchange reaction of sodium stearate and mercury dichloride:

Also, heating mercurious oxide with stearic acid.

The compound forms yellow waxy substance.

It is used as a germicide and as a plasticizer in the production of ceramics.^{[citation needed]}