Potassium ferrocyanide is a chemical compound with the formula K4[Fe(CN)6]. It appears as a yellow crystalline solid and is commonly used in various applications, including as a food additive and in the production of pigments. It is also known as "yellow prussiate of potash." This compound is stable and non-toxic in its typical forms, making it safe for use in food processing. However, it should be handled with care, as it can release toxic cyanide gas under certain conditions. Potassium ferrocyanide is also used in laboratories for analytical chemistry and in the manufacturing of certain dyes.