Thiocyanic acid, also known as thiocyanic acid or isothiocyanic acid, is a chemical compound with the formula HSCN. It is a colorless liquid with a pungent odor, commonly used in organic synthesis and as a reagent in various chemical reactions. Thiocyanic acid is the conjugate acid of the thiocyanate ion, SCN⁻, which is found in some salts. This acid can be produced by the reaction of sulfur with cyanide compounds or by hydrolysis of thiocyanate salts. Thiocyanic acid is important in the study of biochemistry and has applications in agriculture, particularly in the development of pesticides and herbicides.