Abstract: In a process for the manufacture of polychloro-copper phthalocyanines by chlorinating copper phthalocyanines in aluminum chloride/sodium chloride melts at from 110.degree. to 190.degree. C, the improvement wherein from 0.20 to 0.33 part by weight of copper phthalocyanines, per part by weight of melt, is rapidly introduced into the melt at temperatures from the solidification point of the melt to 120.degree. C, and after this material has been introduced, the chlorination, to give polychloro-copper phthalocyanine, is carried out at from 140.degree. to 160.degree. C by rapidly passing chlorine into the mixture. A polychloro-copper phthalocyanine which contains less than 0.05 per cent by weight of aluminum and which can be converted, by any conventional finishing process, into yellowish green pigment forms, is obtained with high space-time yield.