Anatase TiO2 nanofibers (200-300 nm in diameter) with 3-dimensionally (3D) ordered pore structure and high surface area were synthesized by electrospinning technique. The unique combination of partially acetylacetone chelated Ti-alkoxide, viscosity-controlling cum high positive charge balancing agent PVP and structure director F127 yielded nanofibers with ordered mesoporosity similar to the Pm (3) over barm structure. Dynamic heating of the fibers in the temperature range 350-540 degrees C and simultaneous XRD studies revealed that the amorphous to anatase transformation initiated at about 400 degrees C with the retention of 3D mesoporosity up to the final heat-treatment stage. TEM studies also confirmed this. During amorphous to anatase conversion, the surface area decreased from 165 (350 degrees C) to 90 m(2) g(-1) (540 degrees C). The crystalline mesoporous nanofibers showed enhanced photocatalytic activity with reusability.