Electrospinning of poly(hexamethylene terephthalate-co-hexamethylene 2,6-naphthalate), P(HT-co-HN), in chloroform was investigated to fabricate ultrafine fibers. Among P(HT-co-HN) copolymers of different composition, continuous ultrafine fibers were obtained only in the electrospinning of 15-18 wt% P(HT-co-HN28) solution in chloroform and the average diameters of resultant fibers were in the range of 8-10 ${mu}{ extrm}{m}$. When small amounts of benzyl triethylammonium chloride (BTEAC) was added to the P(HT-co-HN) copolymer solutions, the beaded fibers changed into fibrous structure, and the average diameters decreased considerably. The charge density of the P(HT-co-HN) copolymer solutions was found to be a major parameter affecting the morphology and diameter of the electrospun P(HT-co-HN) fibers.