A series of ultrafiltration (UF) membranes were prepared through phase inversion technique by blending cellulose acetate (CA) with poly acrylic acid (PAA) in the blend compositions of 100/0, 99.5/0.5, 98.5/1.5 and 97.5/2.5% blend compositions. Prepared membranes were subjected to membrane characterization studies. Morphological studies revealed the increased number of pores with the addition of PAA, indicating higher fluxes for the blend membranes. Thermal stability of the blend membranes increased with the addition of PAA to the base polymer. UF characterization studies on the blend membranes clearly indicated the increased water uptake and pure water flux with the increase in the concentration of the PAA in the blend composition. Membrane characterization and performance studies clearly indicated the better performance of 97.5% CA - 2.5% PAA blend membrane in comparison with other synthesized UF membranes as well as the pure CA membrane.