This article is about the phenomenon where a liquid can exist in a metastable state above its boiling point. See superheated water for pressurized water above 100 °C. See superheater for the device used in steam engines.

In physics, superheating (sometimes referred to as boiling retardation, or boiling delay) is the phenomenon in which a liquid is heated to a temperature higher than its boiling point, without boiling. Superheating is achieved by heating a homogeneous substance in a clean container, free of nucleation sites, while taking care not to disturb the liquid.