Abstract: Improved eutectic process for preparing polychloro copper phthalocyanine by chlorinating copper phthalocyanine in a reaction medium of molten inorganic metal halide and contacting the reaction medium with an aqueous medium to precipitate the polychloro copper phthalocyanine, wherein the improvement resides in adding a reducing agent to the reaction medium after the completion of the chlorination or to the aqueous medium prior to contact with the reaction medium. The improved process provides a highly chlorinated polychloro copper phthalocyanine which is substantially free of tetrachlorophthalimide impurity. The resulting polychloro copper phthalocyanine is a pure green compound useful as a high quality pigment for a variety of applications.