3-Hydroxypropionic acid is a carboxylic acid, specifically a beta hydroxy acid. It is an acidic viscous liquid with a pKa of 4.5. It is very soluble in water, soluble in ethanol, and miscible with diethyl ether. Upon distillation, it dehydrates to form acrylic acid. 3-Hydroxypropionic acid is used in the industrial production of various chemicals such as acrylates. It can be produced by engineered microbes.