We report a study of the fluorescence properties of the conjugated polymer poly [2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) and polyethylene oxide (PEO) nanofibers. MEH-PPV/PEO nanofibers with different compositions have been fabricated by the electrospinning technique. The fluorescence spectra of the nanofibers show that the emission shoulder at similar to 630 nm blue-shifts similar to 45 nm, whereas the main emission peak around 590 nm blue-shifts similar to 15 nm with decreasing concentration of MEH-PPV in the nanofiber. in addition, confocal microscopic studies of a single MEH-PPV/PEO electrospun nanofiber indicate that the fluorescence spectra of the nanofiber do not show any polarization dependence. The results are discussed in terms of the aggregation of MEH-PPV in an inert matrix. (C) 2009 Elsevier B.V. All rights reserved.