The title compound, 1-keto-4-thioketo-3,6-diphenypyrrolo-[3, 4-c]-pyrrole (MTPP) is a mono-thionated derivative of diketopyrrolopyrrole (DPP) that is known as a novel red pigment on the market. Dithioketopyrrolopyrrole (DTPP) has also attracted attention as a material useful for laser printers as well as optical disks based on GaAsAl laser diodes. Because of the hybrid structure of DPP and DTPP, the electronic structure of MTPP has been characterized in solution and in the solid state in order to explore new electronic applications. The crystal structure of MTPP is found to be isomorphous with modification I of DTPP, The color of MTPP is nearly between DPP and DTPP. The intermolecular hydrogen bonds based on both NH . . .O and NH . . .S are found to be considerably weak as compared with those of DPP (NH . . .O) and DTPP (NH . . .S). The absorption spectrum of evaporated MTPP suggests a potential application for the blue-filter for liquid crystal displays (LCD).