Electrospinning isone of the cheapest and easiest methods to produce single and continuous polymericnanofibers. Conductive nanofibers have many applications as in electrical, optical, thermal, magnetic materialsand devices, energy storage and sensors. Polypyrrole(PPy) is one of theconductive polymers with high electrical conductivity and electrochemical properties. Also, it is an environmentally compatible polymer. PPy has highspecific surface, low basis weight andhigh pores. Itsprocessability is very small; so many attempts have been madeto improveitsprocessability. In this study, hybrid nanofiberof Polypyrrole/Polyacrylonitrilewas produced by in situ polymerization method of polypyrrole. Ammonium persulfate (APS) as the oxidant and dodecyl benzene sulfonic acid (DBSA) as the dopontwere used in polymerization reaction. The effect of temperature and duration of polymerization andpyrrole (Py) concentration on the electrical resistance of nanofiberwebs wasinvestigated. It was observed that the electrical resistance of PAN/PPynanofiberwebs wasincreased by increasing polymerization temperature. This increase in polymerizationduration up to 8 hr tended todecrease the electrical resistance of PAN/PPynanofiber webs, but more duration didn’t show any meaningful change. Also, theresults showed that the increase in Py concentrationup to 9 wt. %caused the decrease in the electrical resistance of PAN/PPynanofiber webs, but the higher concentrations had no significant effect on it. FTIR spectra of PAN/PPynanofibers obviously showed the characteristic absorption peaks related to only polymeric groups ofPAN and PPy. This showed that there was no chemical linkage or interaction between PAN and PPy in the resulting hybrid nanofibers. It was also observed from FESEM images that the surface of nanofiberswas quite smooth and even, showing that the loading of the PPy up to 15 wt. % led to the increase of nano?ber diameters. TGA results alsoshowed that the thermal stability of PAN/PPY nano?bers was increased by the increase in Py concentration. The electrical conductivity of PAN/PPynanofibers was measured by the four- point method. The results showed that the electrical conductivity of PAN/PPynanofiber webs was increased from 10 -15 S/cm for purePAN to 10 -4 S/cm for pure PAN and PAN/PPynanofiber webs. Keywords: Nanofibers, Conductive nanofibers, Polypyrrole, Insitu polymerization, Electrical conductivity.