Thiocyanate (also known as rhodanide) is the anion [SCN]−, a salt or an ester of thiocyanic acid. It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Mercury (II) thiocyanate was formerly used in pyrotechnics.

Potassium cyanide Cyanide of potassium; hydrocyanic acid; potassium salt Carswell No. 688A KCN Chemical structure H+C N Na+C N K+C N Identification numbers: CAS registry 74-90-8 143-33-9 151-50-8 NIOSH RTECS MW6825000 VZ7530000 TS8750000 EPA hazardous waste P063; D003 P106; D003 P098; D003 OHM/TADS 7216749 7216892 7216862