Mohammad Mahdi A. Shirazi - Biofuel Research Team (BRT), Department of Microbial Biotechnology and Biosafety, Agricultural Biotechnology Research Institute of Iran (ABRII), Karaj, Iran.
Meisam Tabatabaei - Biofuel Research Team (BRT), Department of Microbial Biotechnology and Biosafety, Agricultural Biotechnology Research Institute of Iran (ABRII), Karaj, Iran.
Mohammad Javad A. Shirazi - Biofuel Research Team (BRT), Department of Microbial Biotechnology and Biosafety, Agricultural Biotechnology Research Institute of Iran (ABRII), Karaj, Iran.
Yaghoub Mansourpanah - Biofuel Research Team (BRT), Department of Microbial Biotechnology and Biosafety, Agricultural Biotechnology Research Institute of Iran (ABRII), Karaj, Iran. Department of Applied Chemistry, LorestanUniversity, Khorramabad, Iran

Today, membrane separation technologies using polymeric membranes are becoming increasing popular for wide rangeof applications, e.g. in petrochemical industry [1], andbiorefineries [2]. Characterization of such membranes can provide a better and more in-depth understandingin order toevaluate their performance. Two major specifications which could directly affect on the polymeric membranes’ performance are pore size and pore size’s distribution. Variousmethods have been used to measure these parameters, but scanning electron microscopy (SEM) and atomic forcemicroscopy (AFM) are considered as major techniques [3]. Due to the existing differences in the technical procedure of these microscopic methods, the results obtained could be ofsignificant difference. In the present study, elevencommercial polymeric membranes were characterized for their pore size and pore sizedistribution by using both SEM and AFM methods. A comparative study was carried out among the reported values by the manufacturer and the obtained results by the two microscopic methods