Oxidised starches E 1404 are the most popular food grade modified starches but the process of their enzymatic hydrolysis was not investigated, and the functionality of the products of this processing is unknown. The aim of the work was to study the possibility of the application of continuous recycle membrane reactor (CRMR) for the hydrolysis of oxidised starches as well as the estimation of the surface properties of the obtained products. It was found that the application of CRMR for the enzymatic hydrolysis of oxidised starches allowed products to be obtained which reveal surface activity. The effectiveness of the membrane process is strongly influenced by the theological properties of the raw material, which determines fouling phenomena in reaction system. The presence of carboxyl groups in starch macromolecules did not inhibit their enzymatic hydrolysis. The surface properties of enzymatic hydrolysis products do not depend on the degree of oxidation of the investigated starches. Substantial differences of the surface activity for the permeate and retentate fractions were observed. (c) 2006 Elsevier B.V. All rights reserved.