Rubidium oxide is a yellow-brown or yellowish crystalline solid with a chemical formula Rb2O. It is also known as dirubidium oxide or rubidium (I) oxide. It is a strong base and reacts with water to produce rubidium hydroxide.
Due to its highly insoluble nature in water, rubidium oxide is very stable; this makes it a good component to be applied in ceramic, glass and optic structures, as well as in fuel cells in electrochemical applications. It is a bad conductor of electricity. However, this compound is an anhydride, meaning that it reacts with strong reducing agents and acids in redox reactions.