Silver oxide is the chemical compound with the formula Ag₂O. It is a fine black or dark brown powder that is used to prepare other silver compounds.

Silver oxide can be prepared by combining aqueous solutions of silver nitrate and an alkali hydroxide. This reaction does not afford appreciable amounts of silver hydroxide due to the favorable energetics for the following reaction:

With suitably controlled conditions, this reaction can be used to prepare Ag₂O powder with properties suitable for several uses including as a fine grained conductive paste filler.

Ag₂O features linear, two-coordinate Ag centers linked by tetrahedral oxides. It is isostructural with Cu₂O. It "dissolves" in solvents that degrade it. It is slightly soluble in water due to the formation of the ion Ag(OH)−2 and possibly related hydrolysis products. It is soluble in ammonia solution, producing active compound of Tollens' reagent. A slurry of Ag₂O is readily attacked by acids:

where HX = HF, HCl, HBr, HI, or CF₃COOH. It will also react with solutions of alkali chlorides to precipitate silver chloride, leaving a solution of the corresponding alkali hydroxide.

Despite the photosensitivity of many silver compounds, silver oxide is not photosensitive. A significant amount of the oxide reduces to metallic silver at temperatures above 380 °C.

This oxide is used in silver-oxide batteries. In organic chemistry, silver oxide is used as a mild oxidizing agent. For example, it oxidizes aldehydes to carboxylic acids.