Two generations of aliphatic hyperbranched polyester (HBPE) were synthesized from 22-bis(methylol) propionic acid and 1,1,1-trihydroxymethyl propane (TMP) as the core moiety by melt condensation method and were blended with cellulose acetate to prepare asymmetric membrane using a phase inversion process. Characterization of the prepared membranes for thermal behavior and morphological studies also has been made using TGA, DSC and SEM techniques. Water contact angle, pure water flux, water content, hydraulic resistance and molecular weight cut-off determinations were applied in order to study of filtration properties and surface and bulk hydrophilicity of the membranes. FTIR/ATR and contact angle results proved existence of (HBPE) on the surface of modified membranes and (FE-SEM) images have good correlation with flux and MWCOs. The result shows that, the surface hydrophilicity of membranes incorporating HBPE is much higher than pure CA or even (PEG-600) modified CA membranes. Furthermore, results show CA-HBPE membranes have lower flux and MWCOs, higher hydraulic resistance and better thermal and mechanical properties in comparison to the membranes modified by linear pore-forming agent. (C) 2014 Elsevier B.V. All rights reserved.