The subject of the invention is a process for the manufacture of condensation products of hydroxymethyl-phosphonium compounds and a cyclic urea, characterized in that (a) 1 mol of a tetrakis(hydroxymethyl)-phosphonium compound is condensed at 40* to 120*C with (b) 0.02 to 0.5 mol, preferably 0.1 to 0.3 mol, of an optionally N-methylolated monocyclic or bicyclic urea, which has 5 to 6 members per ring, optionally in the presence of formaldehyde or a formaldehyde-releasing agent and optionally in the presence of an inert organic solvent, if appropriate, condensation is thereafter continued at 100* to 150*C and if appropriate free hydroxyl groups are at least partially etherified with at least one alkanol with 1 to 4 carbon atoms and if appropriate the salts of the polycondensation products are converted into the corresponding hydroxides. The condensation products are used for flameproofing organic fibre material, in particular textiles.