Abstract: Novel emulsifiable prepolymers for polyurethanes comprising an isocyanate prepolymer a minor proportion of the terminal isocyanate groups of which have been reacted with a quaternized tertiary amino alcohol, storage stable polyurethane latices produced therefrom and methods of making them are described. In a preferred embodiment a conventional isocyanate terminated prepolymer is first produced by the reaction of a polyol, preferably a diol of polyether or polyester origin, with a stoichiometric excess of a polyisocyanate, preferably a diisocyanate such as toluene diisocyanate; this prepolymer is then reacted, under anhydrous conditions, with a small amount, usually from about 1% to 5%, preferably about 1% to about 2%, by weight of a quaternized tertiary amino alcohol. Alternatively, a small amount of the quaternized tertiary amino alcohol may be included in the mixture of polyol and excess isocyanate used for making the prepolymer.