Method of making color changing inkjet inks for security printing applications use photochromic materials that cause the inkjet ink to print marks that are colorless under ambient light and appear in a color when exposed to sunlight or UV light (covert). In another embodiment, the printed mark appears in a first color under ambient light, and changes to a second color when exposed to sunlight or UV light (overt). The methods of making the photochromic inks produce ink components that are stable and maintain their color changing capability for the shelf life of the printed material. The inkjet ink formulations are suitable for use on porous and non-porous surfaces, such as plain paper, coated paper, Teslin, polymer film, ceramic or metal, for example.