In this communication, we first report a novel route to synthesize centimeter-scaled polyaniline (PANi) fiber in the presence of oligo-acrylamide (OAAm). The Fourier transform infrared and ultraviolet-visible spectra reveal that the fiber is copolymers of PANi and PAAm, and PANi is in high conductive emeraldine salt state. Acrylamide feed significantly affects the morphology of the fiber, the conductivity and yield of the fiber depend on hydrochloric acid and potassium peroxydisulfate concentration in the preparation process. Under optimized conditions, a hexagonal PANi/PAAm fiber with conductivity of 3.7 S cm(-1) and length of 6 cm is obtained, which provides a facile method for preparing conductive long fiber. It is proposed that the oligo-acrylamide acted as in-situ seeds directs the fibriform morphology of the fiber. (C) 2008 Elsevier Ltd. All rights reserved.