Potassium ferricyanide is the chemical compound with the formula K3[Fe(CN)6]. This bright red salt contains the octahedrally coordinated [Fe(CN)6]3− ion. It is soluble in water and its solution shows some green-yellow fluorescence. It was discovered in 1822 by Leopold Gmelin.

Leopold Gmelin was a German chemist. Gmelin was a professor at the University of Heidelberg. He worked on the red prussiate and created Gmelin's test, and wrote his Handbook of Chemistry, which over successive editions became a standard reference work still in use.