Abstract: A process is disclosed for preparing chlorinated pyridinesulphonic acid chlorides of the general formula I from hydroxypyridine-sulphonic acids of the general formula II The process generally entails a) passing chlorine gas into a mixture of a hydroxypyridine-sulphonic acid and of phosphorus trichloride; b) heating the mixture of a) to temperatures of about 100 to about 120° C.; c) removing any phosphorus oxychloride formed and any excess phosphorus trichloride by distillation; d) taking up the residue with an organic solvent; and e) distilling the liquid phase in a vacuum, thereby obtaining the chlorinated pyridine-sulphonic acid chloride.