Blending allows to tailor and modulate the properties of selected polymers. Blends of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polyethylene oxide (PEO) were fabricated by electrospinning in different weight ratios Le. 100:0, 80:20, 70:30, 50:50,0:100. In order to evaluate the influence of PEO addition on the final properties of PHBV, a complete microstructural, thermal and mechanical characterization of PHBV/PEO blends has been performed. The two neat polymeric membranes were also considered for the sake of comparison. The following characterization techniques were employed: scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy, simultaneous thermogravimetric and differential analyses (TG-DTA), differential scanning calorimetry (DSC), and uniaxial tensile tests. All electrospun mats consisted of randomly oriented and uniform fibers. It has been observed that the microstructure of PHBV/PEO was remarkably affected by blend composition. The average fiber size ranged between 0.5 mu m and 2.6 mu m. It resulted that the electrospun polymeric blends consisted of separate crystalline domains associated to an amorphous interdisperse phase. PHBV/PEO blends presented intermediate mechanical properties, in terms of tensile modulus and ultimate tensile stress, with respect to the two neat components. (C) 2012 Elsevier B.V. All rights reserved.