Hexacyanoferrate is a complex ion composed of iron and cyanide groups, represented by the formula Fe(CN)₆^4- or Fe(CN)₆^3-. It is commonly found in two forms: ferrocyanide (with iron in the +2 oxidation state) and ferricyanide (with iron in the +3 oxidation state). These compounds are often used in various applications, including pigments, electrochemistry, and as a precursor in the synthesis of other chemical compounds. Hexacyanoferrate compounds are notable for their stability and ability to form coordination complexes. They are used in the production of Prussian blue, a pigment, and in the field of analytical chemistry for detecting certain metal ions. Additionally, hexacyanoferrate plays a role in the development of battery technology and as a treatment for cyanide poisoning.