Poly(ethylene-co-vinyl acetate)/clay nanocomposite fibers were fabricated using electrospinning. The fiber diameters were controlled by varying the polymer/chloroform concentration, which resulted in fibers with diameters ranging from 1 to 1.5 mu m. The clay concentration was varied from 0.35 to 6.6 wt % Scanning electron microscopy revealed that the fiber diameter increased with increasing clay concentration, whereas beading decreased. Transmission electron microscopy revealed a disruption of the spherulite structures by clay, which is consistent with heterogeneous nucleation Shear modulus force microscopy indicated a reduction in melting point (T-m) with decreasing diameter for fibers thinner than 15 mu m, which was confirmed by temperature dependent X-ray diffraction data. For fibers thinner than 8 mu m, the presence of clay further enhanced the reduction of T-m. (C) 2009 Wiley Periodicals, Inc J Polym Sci Part B. Polym Phys 47 2501-2508, 2009