Calcium ferrocyanide is an inorganic compound with the formula Ca<sub>2</sub>[Fe(CN)<sub>6</sub>]. It is the Ca<sup>2+</sup> salt of [Fe(CN)<sub>6</sub>]<sup>4-</sup>, ferrocyanide complex ion. It is insoluble in water, acids, and organic solvents. A yellow solid, it is used as a precursor to the pigment Prussian blue.
It was listed in 2012 by the EU as a "Food Improvement Agent".
In the EU, ferrocyanides (E 535âÂÂ538) were, as of 2018, solely authorised in two food categories as salt substitutes. Kidneys are the organ for ferrocyanide toxicity.