Propanethiol is an organic compound with the molecular formula C₃H₈S. It belongs to the group of thiols. It is a colorless liquid with a strong, offensive odor. It is moderately toxic and is less dense than water and slightly soluble in water. It is used as a chemical intermediate and a herbicide. It is highly flammable and it gives off irritating or toxic fumes (or gases) in a fire. Heating it will cause rise in pressure with risk of bursting.