There are described novel porphyrin derivatives of the general formula ##STR1## wherein either R.sup.1 signifies the group ##STR2## and R.sup.2 signifies the group ##STR3## or R.sup.1 signifies the group ##STR4## and R.sup.2 signifies the group ##STR5## whereby X.sup.- signifies a halogen ion, an arylsulphonate ion, an alkylsulphonate ion or an alkyl sulphate ion, A signifies (C.sub.1-8)-alkylene and R.sup.3 signifies (C.sub.1-4)-alkyl,and sulphonic acid salts of compounds of formula I in which R.sup.1 signifies the group ##STR6## as well as a process for their manufacture and intermediates used in this process.Because of their water-solubility the novel porphyrin derivatives are suitable as label molecules for highly sensitive fluorescence immuno-assays, especially for time-resolving fluorescence immuno-assays. The coupling of the novel porphyrin derivatives to immunologically-active materials is carried out in the customary manner, for example with a water-soluble carbodiimide derivative.