Novel composite nanofibrous membranes with potential application on the biomedical application were successfully developed via electrospinning of poly(3-hydroxybutyrate co 4 hydroxybutyrate)(P(3HB-co4HB)) and cellulose acetate(CA) blend solution. The ultra-fine fiber structure was observed by SEM and the composite nanofibers exhibited cylindrical, uniform, bead-free and random orientation with the diameter ranged from 100 to 600 nm. The structure of composite nanofiber membranes were characterized by X-ray diffraction test. The biodegradability was evaluated by in vitro degradation test and the results revealed that the composite nanofibers show much higher degradation rates than the neat P (3HB-co-4HB). (C) 2016 Elsevier B.V. All rights reserved.