Highly porous (similar to 70%) polyaniline-carbon black composite nanofiber mats with good conductivity were fabricated via electrospinning. The fiber mat was electrospun using polyvinyl alcohol as carrier solution which was later decomposed at similar to 230 degrees C to get a complete conducting nanofiber network. This heat treatment reduced the fiber diameter from similar to 250 nm to similar to 170 nm and the porosity of the fiber mat increased from similar to 41% to 70%. The removal of the carrier phase was confirmed by Fourier transform infrared spectroscopy and did not result into any structural collapse. The localized conductance measurements using scanning electrochemical microscopy showed that the removal of insulating carrier solution substantially reduced the percolation threshold and increased the fiber-mat conductance. (C) 2011 Elsevier B.V. All rights reserved.