Temperature-responsive flat composite ultrafiltration membranes were prepared by dry-wet phase inversion process from casting solution of polyacrylonitrile and hydrophobically modified polyvinyl alcohol (HMPVA) in dimethylsulfoxide solvent. HMPVA is characterized by multiple reversible temperature-stimulated change of its physicochemical properties with the temperature of transformation (T (tr)) being dependent on the degree of acetalization. Based on the dynamic viscosity, the limit of the polymer concentration in the solution was established to be from 0.6 to 3.5 wt% for HMPVA at constant concentration of 16 wt% PAN. HMPVA remained homogeneously scattered within the membrane structure which was proved by Fourier transform infrared spectroscopy (FTIR). The studies on membrane morphology by scanning electron microscopy and on permeability (J, l/m(2) h) and rejection (R, %) for water and albumin showed an asymmetry of the porous structure with pores having capillary macroporosity-on the surface and inner walls of the pores. The optimal for membrane parameters is a concentration of 1.2 wt% HMPVA. The permeability to water at 0.3 MPa changes from 58 to 80 l/m(2) h and permeability to albumin-from 30 to 56 l/m(2) h, when changing the temperature relative to T (tr) = 29.5 A degrees C. Adjusting the temperature, it allows us to control the amount of flow passing through the membrane and widens the possibilities for self-cleaning and regenerations of the membrane.