A phosphoric ester demulsifier composition prepared by reacting one or more alkylphenol-formaldehyde resin alkoxylates or one or more polyalkylene glycols, or a mixture thereof, with about 0.001 to about 1.0 molar equivalents of one or more phosphorous compounds selected from phosphorous oxychloride, phosphorous pentoxide and phosphoric acid and a method of using the demulsifier composition to resolve water-in-oil emulsions.