The biogas produced from the anaerobic fermentation of palm oil mill effluent (POME) contains equal amount of H-2 and CO2, in which the biohydrogen (bioH(2)) is a prospective source of renewable energy. Therefore, the determination of an efficient H-2 purification technique has been a major concern. Membrane separation technology is highly recommended due to its excellent purification performance with high permeation of H-2 and H-2/CO2 selectivity. Polymer blending is a favourable approach due to its simplicity to refine membrane inner structural properties by combining different polymers with complementary features. In this study, the synthesized polysulfone-polyimide (PSf/PI) membrane is an alternative polymeric membrane practicable for H-2/CO2 separation due to its outstanding permeation properties, enhanced membrane properties as well as improved tolerance to plasticizing gases. The effect of evaporation time on PSf/PI membranes was further investigated and was thoroughly characterized by FHA, TGA, DSC and SEM. The miscibility of the PSf/PI blending was proven by DSC with the detection of only single glass transition temperature value. The highest permeability of both H-2 and CO2 gas were presented by PSf/PI-60 membrane with 348 GPU and 86 GPU, respectively, H-2/CO2 selectivity of 4.4 and H-2 purification efficiency of 80%. Hence, PSf/PI membrane is a high potential candidate with inherent properties for H-2/CO2 separation from POME fermentation.