The electrochemical properties of Prussian blue films on Pt and spark anodized n‐type electrodes were investigated. Evidence for four redox states for Prussian blue was obtained. While the oxidation of Everitt's salt to Prussian blue involves the high spin iron atoms, the oxidation of Prussian blue to Berlin green and Berlin green to Prussian yellow involves the low spin hexacyanoferrate groups. The Prussian blue/Everitt's salt redox system ( vs. SCE) is the most stable and reversible couple. The diffusion coefficients for reduction and oxidation of this redox couple are , respectively. The photoelectrochromic behavior of Prussian blue on semiconductor electrodes is discussed. The films deposited on have short‐circuit memory, and lateral color spreading through the film is slow. A light addressable electrochromic display is described.