Conducting polyacrylonitrile (PAN) nanofiber mats were prepared by dipping non-woven nanofiber mats of PAN in the solution of poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS). PAN nanofiber mats were fabricated via the electrospinning process. The solvent used for PEDOT/PSS was ethylene glycol and isopropanol. The morphology of the resulting PAN nanofibers and the coating layers was investigated using SEM analysis. The electrical conductivity of PEDOT/PSS coated PAN nanofiber mats was measured by the four-point probe method, for different concentrations of solvent in the PEDOT/PSS solution. An addition of ethylene glycol resulted in higher electrical conductivity of the coated mats than that of isopropanol. The resistive humidity sensing properties were also investigated. The device reproducibility was presented by vapor adsorption/desorption dynamic cycles. The reproducibility of the PEDOT/PSS coated mats was superior to that of neat PEDOT/PSS films. The response sensitivity of coated mats using isopropanol as solvent was higher than that using ethylene glycol.