A commercialized polysulfone (PSf) hollow-fiber membrane module was tested for CO 2 /N 2 separation performance for application in post-combustion capture. Cost efficiency, easy module manufacturing, and efficiency in gas separation are the main advantages of using PSf hollow-fiber modules for CO 2 separation. The effects of operating conditions such as temperature, pressure, and feed composition on separation performance were examined at various stage cuts. A 2-stage system including concentration of feed composition at stage 1 and production of high-purity CO 2 at stage 2 was constructed to improve separation efficiency. Higher operating temperature and pressure increased CO 2 permeance, but the loss of selectivity and higher energy consumption are a concern. Modules with various membrane areas were also used to test the effect of area on CO 2 separation.