Submicrometer polyacrylonitrile (PAN) hollow fiber membranes were fabricated via concentric electrospinning and were assembled into a filtration module. The module operated in an "inside-out" mode where a feed solution is introduced through the lumen while filtrate is collected from outside the fiber wall through a side arm. The relatively smooth PAN fibers exhibited 530 and 890 nm average inner and outer diameters, respectively. The performance of the hollow fibers was tested by filtering an Indigo carmine dye and NaCl solutions. The dye solution passed through the PAN fibers, and the filtrate was colorless indicating that water but not dye permeates through the fiber walls. In a similar fashion, the NaCl solution was desalinated with 97.796 +/- 0.6 salt rejection.