Methyldiethanolamine is an organic compound with the chemical formula C5H13NO2. It is a colorless or dark yellow oily liquid that is miscible with water and alcohol, and slightly soluble in ether. It is mainly used as emulsifier and acid gas absorber, acid base control agent, polyurethane foam catalyst, and also as an intermediate of antineoplastic drugs such as nitrogen mustard hydrochloride.

It is widely used as an emulsifier for desulfurization and purification of oil field gas and gas, as well as an acid gas absorber, an acid base control agent, and a polyurethane foam catalyst. It can remove carbon dioxide from synthetic ammonia with the participation of an activator. It can also be used as a semi-finished product of pesticides, emulsifiers, fabric additives, intermediates of the anti-tumor drug nitrogen mustard hydrochloride, catalysts for carbamate coatings, fiber additives, etc. It is also a drying promoter for paints.