A process for the manufacture of blown, cellular polyurethanes by the reaction of a polyisocyanate with water and a hydroxyl-containing polymeric material, such as a polyester or polyether, is characterised in that there is incorporated therein a preformed tertiary amine salt of a compound containing one or more-SO3H or OSO3H groups and a hydrocarbon radical containing at least 12-carbon atoms. The salt can be prepared in the anhydrous state or in water either from stoichiometric proportions of its components or with an excess of one component. Specified compounds containing-SO3H or -OSO3 H groups are dodecylsulphuric acid, oleyl-p-anisidine sulphonic acid, dodecyl benzene sulphonic acid, sulphuric acid esters of long chain alcohols such as cetyl alcohol, dinaphthyl methane disulphonic acid, diisopropyl naphthalene sulphonic acid and the sulphated methyl ester of oleic acid. The tertiary amine may contain substituents, for example carboxyl, urethane, urea, keto, amide or hydroxyl groups or hetero atoms or heterocyclic rings. Specified are triethylamine, triethanolamine, b -diethylamino ethanol, bis-(b -diethylaminoethyladipate, b -diethylaminoethyl benzoate, b -diethylaminopropionitrile, dimethyl octadecylamine, N-dimethyl cyclohexylamine and N-dimethylbenzylamine. The salts may be added as such or as aqueous solutions, pastes or emulsions. Amine soaps, e.g. diethylamine oleate and diethylamino ethanol ricinoleate may also be present in the reaction mixture. Fillers, colouring matters, flame-proofing agents may be added to the reaction mixture as dry powders or as pastes with, for example, the hydroxyl containing material, the polyisocyanate, tricresylphosphate or water. Iron compounds and organopolysiloxanes can also be added. In examples foams are obtained from (1) a diethylene glycol/pentaerythritol/adipic acid polyester, toluene 2:4- and 2:6-diisocyanates and an aqueous mixture obtained by neutralising 1-dodecyl sulphuric acid with N-dimethyl cyclohexylamine; (2) a diethylene glycol/glycerol/adipic acid polyester, tolylene 2:4 and 2:6-diisocyanates and an aqueous mixture of the neutralisation product of N-oleyl p-anisidine sulphonic acid with 2diethylaminoethanol; (3) a polypropylene glycol/trimethylol propane/tolylene 2:4 + 2:6-diisocyanate prepolymer, further tolylene diisocyanates and an aqueous mixture of the salt of-b diethylaminoethanol and the sulphated methyl ester of oleic acid. Specifications 553,733, 770,632, 790,420 and 839,183 are referred to.ALSO:Catalysts for use in the production of polyurethanes (see Groups IV(a) and V) comprise a preformed tertiary amine salt of a compound containing one or more -SO3H or -OSO3H groups and a hydrocarbon radical containing at least 12 carbon atoms. For the latter are specified dodecyl-sulphuric acid, oleyl-p-anisidine sulphuric acid, dodecylbenzene sulphonic acid, sulphuric acid esters of long chain alcohols such as cetyl alcohol, dinaphthyl methane disulphonic acid, diisopropyl naphthalene sulphonic acid and the sulphated methyl ester of oleic acid. The tertiary amine may contain substituents, for example carboxyl, urethane, urea, keto, amide or hydroxyl groups or hetero atoms or hetero-cyclic rings. Specified are triethylamine, triethanolamine, b -diethylaminoethanol, bis-(b -diethyl-aminoethyl) adipate, b -diethylaminoethyl benzoate, b -diethyl aminopropionitrile, dimethyl octadecylamine, N-dimethylcyclohexylamine and N-dimethylbenzylamine. In examples the salts employed are prepared from (1) 1-dodecyl sulphuric acid and N-dimethyl cyclohexylamine, (2) N-oleyl p-anisidine sulphonic acid and 2-diethyl-aminoethanol; (3) the sulphated methyl ester of oleic acid and b -diethylaminoethanol. Specification 790,420 is referred to.ALSO:A process for the manufacture of blown, cellular polyurethanes by the reaction of a polyisocyanate with water and a hydroxy-containing polymeric material, such as a polyester or polyether is characterised in that there is incorporated therein a preformed tertiary amine salt of a compound containing one or more -SO3H or -OSO3H groups and a hydrocarbon radical containing at least 12 carbon atoms. The salt can be prepared in the anhydrous state or in water either from stoichiometric proportions or with an excess of one component. Specified compounds containing -SO3H or -OSO3H groups are dodecyl-sulphuric acid, oleyl-p-anisidine sulphonic acid, dodecyl benzene sulphonic acid, sulphuric acid esters of long chain alcohols such as cetyl alcohol, dinaphthyl methane disulphonic acid, diisopropyl naphthalene sulphonic acid and the sulphated methyl ester of oleic acid. The tertiary amine may contain substituents, for example carboxyl, urethane, urea, keto, amide or hydroxyl groups or hetero atoms or heterocyclic rings. Specified are triethylamine, triethanolamine, b -diethyl-aminoethanol, bis p (b -diethylaminoethyl) adipate, b -diethylaminoethyl benzoate, b -diethylaminopropionitrile, dimethyl octadecylamine, N-dimethylcyclohexyl-amine and N-dimethylbenzylamine. The salts may be added as such or as aqueous solutions, pastes or emulsions. Amine soaps e.g. diethylamine oleate and diethylamino-ethanol ricinoleate may also be present in the reaction mixture. Fillers, colouring matters, flame proofing agents may be added as dry powders or mixed with a reortant, tricresyl phosphate or water. Iron compounds and organopolysiloxones can also be added. In examples foams are obtained from (1) a diethylene glycol/pentoereythritol/adipic acid polyester, toluene 2 : 4- and 2 : 6- diisocyanates and the aqueous solution of the salt of 1-dodecyl sulphuric acid with N-dimethyl cyclohexyl-amine; (2) a diethylene glycol/glycerol/adipic acid polyester, tolylene 2 : 4- and 2 : 6 diisocyanates, water and the salt of N-oleryl-p-anisidine sulphonic acid with 2-diethyl-aminoethanol; (3) a polypropylene glycol/trimethylol propane/tolylene 2 : 4 and 2 : 6- diisocyanates prepolymer, further tolylene diisocyanates and an aqueous mixture of the salt of b -diethylaminoethanol and the sulphonated methyl ester of oleic acid. Specifications 553,733, 770,632, 790,420 and 839,183 are referred to.