Process comprising (I) reacting (a) at least one polyisocyanate or mixture of polyisocyanates which contains at least three isocyanate groups per molecule with (b) a stoichiometric deficiency of at least one fluorochemical compound which contains per molecule (i) a single functional group having one or more Zerewitinoff hydrogen atoms and (ii) at least two carbon atoms each of which contains at least two fluorine atoms, and (II) thereafter forming one or more urea linkages per mol of said polyisocyanate by reacting the remaining isocyanate groups with water in an amount sufficient to to react with from about 5% to about 60% of the isocyanate groups in said polyisocyanate.