Ultrafine polystyrene (PS)/poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV) fibers were successfully prepared by electrospinning of PS/ MEH-PPV solutions in chloroform, 1,2-dichloroethane, and tetrahydrofuran (THF). Three concentrations of the solutions were prepared: 8.5, 16, and 23.5% (w/v), with the compositional weight ratios between PS and MEH-PPV being 7.5:1, 15:1, and 22.5:1, respectively. Smooth fibers only observed from 23.5% (w/v) PS/MEH-PPV solution in chloroform. Improvement in the electrospinnability of 8.5% (w/v) PS/MEH-PPV solution in chloroform was achieved by addition of an organic salt, pyridinium formate (PF), or by addition of a minor solvent with a high dielectric constant value. The average diameters of the as-spun PS/MEH-PPV fibers were between 0.30 and 5.11 mu m. Last, photolumineseence of 8.5% (w/v) solutions of PS/MEH-PPV in a mixed solvent system of chloroform and 1,2-dichloroethane of various volumetric compositions and the resulting as-spun fibers was investigated and compared. (c) 2005 Wiley Periodicals, Inc.