In this article the data of the purification of water steam condensate of the LLP «Pavlodar Petrochemical Plant» is considered. In the course of research multifunctional ion exchangers for pre-filters synthesized and were studied. A pilot reverse osmosis unit was produced with a capacity of 600 L per hours, and had been tested to clean steam condensate using a «Unit of Electromagnetic Treatment» (UET) and without it. The optimal treatment mode of purification was selected to the separation of the concentrate 0.1 m 3 per hour. It was found that after desalination of water acidity value of pH changed to acidic medium (permeate) or to the basic medium in the concentrate tract, which associated by decreasing or increasing hydrocarbonate ions, accordingly, in permeate and concentrate. It was noted that the using of the UET at the inlet, led to a slight decreasing of the operating pressure inside the reverse osmosis unit, while on the reverse osmosis unit without UET it corresponded to the calculated value. It was established that the membranes used in testing by using the UET practically have no deposits on themselves, and without it they have a noticeable amount of contamination on their surface. Thus, using the UET in the process of reverse osmosis desalination can significantly increase the service life of membranes and maintain their selectivity, and the proposed method allows to achieve the required water purification standards set by the plant.