Conductive composite fibers of polyaniline doped with dodecylbenzene sulfonic acid (PANI-DBSA) and polyacrylonitrile containing methylacrylate (Co-PAN) were prepared via a conventional wet spinning process. The influences of PANI-DBSA content on the electrical conductivity, thermal stability and mechanical properties of the composite fibers were investigated. The fiber with 7 wt% PANI-DBSA showed its conductivity of an order of 10 –3 S/cm. The tensile strength of the fibers was in the range of 2.5–3.5 cN/dtex. The thermal stability of the composite fiber was superior to both pure Co-PAN and PANI-DBSA. It was observed through scanning electron microscope (SEM) and transmission electron microscope (TEM) that nanosized dot-like PANI-DBSA was well dispersed within Co-PAN matrix.