The process of synthesis of 1(st)-, 2(nd)- and 3(rd)-generation dendritic polyamidoamines (PAMAM), using ammonia and ethylenediamine, is described. It is shown that the oil drops disintegration rate constant and the degree of breakdown of a stable oil-water emulsion increase with each subsequent generation of the dendrimer and with its increasing concentration. The maximally attained degree of separation of water containing 68 mg/L of oil was 84.6% with the addition of 20 mg/L of 3rd-generation PAMAM. The demulsification mechanism is shown to be associated with the spherical shape of the dendritic PAMAM macromolecules and the presence of a large number of polar amino functional groups on the surface of these spheres.