Lipopolysaccharides are compounds of bacterial origin that have biological activity against plants, animals and humans. This work provides information on the preparation and characterization of the properties of modifi ed lipopolysaccharide derivatives of the rhizosphere bacterium Ochrobactrum cytisi IPA7.2. Deacylation has been carried out using alkaline hydrolysis, followed by chromatographic separation of the fractions. O-deacetylation of O-polysaccharide led to a 2-fold increase in the extinction of the products of the phenol-sulfuric acid reaction.