LH2 is an acronym used in the aerospace industry, which stands for Liquid Hydrogen. LH2 is a common liquid fuel for rocket applications. Hydrogen is found naturally in the H₂ form, thus the H2 part of the name. Hydrogen at normal temperatures is a gas and to exist as a liquid must be cooled to a very low level, 20.268 K (−423 °F).

Liquid hydrogen has a very low density of 70.8 kg/m³ (at 20 K), so storage tanks for it have to be quite large.

See also: Compressed Gaseous Hydrogen (CGH2).