This invention relates to new aromatic uretdione-diisocyanate-disulphonic acids, to a process for the preparation thereof and to the use thereof as components for the production of polyurethane resins. More particularly, the instant invention relates new aromatic uretdione-diisocyanate-disulphonic acids of the general formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 each represent a hydrogen, chlorine or bromine atom or a methyl, ethyl or C.sub.1 -C.sub.4 alkoxy group;x represents --O--, >C.dbd.O, >SO.sub.2, ##STR2## or --CH.dbd.CH-- wherein R.sub.7 and R.sub.8 each represent a hydrogen atom, a methyl or ethyl group or, when taken together with the carbon atom to which they are attached represent a cyclohexyl group; andn represents 0 or 1.These novel compounds are prepared by reacting a diisocyanate of general formula: ##STR3## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, n and x are as defined above with SO.sub.3 at temperatures of from -30.degree. to +100.degree. C. in anhydrous solvents which are inert towards SO.sub.3 and isocyanate groups.