Abstract: A process for producing microporous sheet materials which comprises the step of:(1) preparing a suspension in an organic solvent of a polyurethane elastomer containing polyoxyethylene segments with or without a polyurethane elastomer not containing these segments;(2) mixing the resulting organic solvent suspension with water in an amount of not less than 50% by weight based on the polyurethane elastomer in the organic solvent suspension to form a water-in-oil dispersion;(3) coating or impregnating a substrate with the resulting dispersion;(4) if desired, partially evaporating the organic solvent from the product so treated;(5) contacting the coated or impregnated substrate for a short period of time with a coagulant having a coagulation value of not more than 25%, and(6) drying the product obtained in step (5).