Processed gas streams from the water gas shift reactor (WGSR) are enriched with CO2 and H2. Purification of H2 from CO2 for different applications is required because of its environmental and economic benefits. Among different separation technologies, membrane technology gets much attention due to its various advantages. In this work, cellulose acetate/polysulfone blended membranes were fabricated via solution casting method for CO2/H2 separation. The separation performance of pure CA membrane was enhanced by addition of PSF. The fabricated membranes were analyzed through various characterization techniques, such as FTIR, SEM, DSC, and XRD. Gas permeation results show that permeability of CO2 increased with increasing concentration of PSF. Notable permeability (P=80.51 Barrer) of CO2 and selectivity of CO2/H2=1.83 of CA/PSF 2wt% were achieved at 25 °C and 2.5 bar compared to pure CA membrane. To the best of our knowledge, this blend has been studied for the first time for gas separation, prepared through the solution casting method.