A series of poly(amide-co-poly(propylene glycol)) (PA-PPG) random copolymers with different content of PPG were designed by polycondensation reaction. These random copolymers were blended up to 60% with commercially available Pebax 2533. The blend membranes were characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM). Gas permeation properties of these blend membranes were investigated using five single-gases (CO2, H-2, O-2, CH4, and N-2) at different temperature of 25-55 degrees C and 1.0atm. The impacts of content of PA-PPG with different PPG content and operating temperature on CO2 separation properties of Pebax/PA-PPG blend membranes were studied. The results showed that CO2 permeability gradually increased with the increasing operating temperature, whereas CO2 permeability gradually decreased with the increase in content of PA-PPG. CO2/N-2 selectivity gradually increased with the increase in content of PA-PPG. In particular, Pebax/PA-PPG (50)-60% displayed excellent CO2 and O-2 separation properties (P-CO2=79.7 Barrer and P-O2=13.6 Barrer, CO2/N-2=34.7 and O-2/N-2=5.9) at 25 degrees C and 1.0atm. POLYM. ENG. SCI., 59:E14-E23, 2019. (c) 2018 Society of Plastics Engineers