This paper reports a novel study focused on the preparation of non-beaded ultrafine uniform nanofibers with a narrow fiber diameter distribution from fluorinated polyimide by electrospinning. Increasing the viscosity of the polymer solutions by the addition of hexamethylenediamine (HMDA) as a cross-linking agent can result in electrospun nanofibers with a smaller diameter. The cross-linking reaction between the polyimide and HMDA was examined by FTIR-ATR and GPC under different cross-linking times. The ultrafine uniform nanofibers were achieved with the use of HMDA. Finally, we successfully prepared the non-beaded ultrafine uniform nanofibers within a narrow nano-range (27 +/- 5 nm). (C) 2012 Elsevier Ltd. All rights reserved.