The aim of the present study is to develop a Y3Al5O12:Ce (YAG:Ce) nanofiber-based phosphor layer for white-light-emitting diodes (WLEDs). The nanofiber was prepared by sol gel and electrospinning methods with a diameter of 250-350 nm. Phase transitions from gel fiber to YAG fiber were well investigated by X-ray diffraction and thermal analysis. The results confirmed that a pure YAG phase formed at around 840 degrees C through direct crystallization of amorphous material. With strictly-controlled annealing process, the fiber morphology was well retained and the fiber-based phosphor layer could be obtained. The diameter of the fiber shrunk to 200-250 nm. WLED device was eventually obtained by directly coating a blue LED chip with the phosphor layer, without dispersion in resin. The packaged white LEDs exhibited a high luminous efficiency of 62 lm/W which was comparable with common commercial white LEDs (similar to 80 lm/W). Furthermore, a tunable Correlated Color Temperature was achievable by controlling the thickness of the layer. (C) 2015 Published by Elsevier Ltd and Techna Group S.r.l.