Poly(amido amine) (PAMAM) dendrimer-polyethylene oxide (PEO) nanofibers as dendrimeric-polymeric composite nanofibers were prepared via electrospinning of PEO Solution containing PAMAM dendrimer. The resultant fibers were characterized by means of transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The morphology and thermal properties of PEO nanofibers with and without PAMAM dendrimer were compared and the effect of PAMAM concentration on morphology and thermal properties of the resultant fibers was studied. The fibers had a size range of about 400-1300 nanometer in diameter with aureole morphology in most regions. The phase change temperature, phase transition heat, and the crystallinity of the produced composite fibers were determined by DSC analyses. TGA was also used to confirm the presence of PAMAM and to determine the amount of it within the fibers. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 3005-3011, 2009