Liquid Air was the brand name of an unusual automobile produced by a joint American/English concern between 1899 and 1902.

Liquid air is air that has been cooled to very low temperatures (cryogenic temperatures), so that it has condensed into a pale blue mobile liquid. To protect it from room temperature, it must be kept in a vacuum insulated flask. Liquid air can absorb heat rapidly and revert to its gaseous state. It is often used for condensing other substances into liquid and/or solidifying them, and as an industrial source of nitrogen, oxygen, argon, and other inert gases through a process called air separation. Liquid air is also replacing liquid nitrogen for theatrical smoke and fog effects.