Glycerine, also spelled glycerin, is a kind of organic compound known as sugar alcohol with a chemical formula C3H8O3. It occurs as a sweet-tasting, viscous liquid that is colorless and odorless. It is miscible in water and generally non-toxic. In nature it occurs in form of glycerides. The glycerides are esters of the compound and are fundamental components of lipids.

Various industries see glycerine in numerous applications. It is included in pharmaceutical preparations due to its lubricating and hygroscopic properties. Thus it is found in cough syrups, expectorants, and suppositories. In personal care products it is found in shaving creams, soaps, mouthwash, toothpastes, skin moisturizers and conditioners, and hair care products. The substance is an excellent solvent. It serves as a humectant (moisture-retaining agent) and a softener in candy and cakes, as well as a food preservative.

A molecule of glycerine or glycerol contains three chains of carbon. In each carbon atom a hydroxyl group is attached. The hydroxyl group is represented as OH. The compound owes its high solubility in water and its hygroscopic nature to the hydroxyl groups. A compound that is hygroscopic has the property of attracting water molecules from the air or from the surrounding. When hygroscopic substances are used for the purpose of retaining moisture, they are accurately referred to as humectants. Glycerol melts at 18°C and boils at 290°C under standard conditions.