Abstract: A process for preparing a soft flexible polyurethane foam by reacting (a) one or more organic polyisocyanates with (b) one or more polyols having a molecular weight in the range from about 400 to about 12,000, in the presence of (c) a catalyst, (d) a blowing agent, and (e), if desired, auxiliaries and/or additives, wherein the blowing agent (d) comprises water in admixture with about 0.01 to about 1 pbw, per 100 pbw polyol (b), of one or more non-crosslinked organic polyelectrolytes having a molecular weight in the range from about 1000 to about 20,000,000.