Gold nanoparticles (AuNP) were formed in situ, while electrospinning a polyacrylonitrile (PAN) solution of HAuCl4 under UV light without using heat or chemical reducing agents. The resulting fibers were purple in color due to the formation of AuNP inside and on the surface of the nanofibers. TEM images showed spherical and uniformly dispersed particles inside the polymer fibers. The concentration of Au+3 in the PAN solution is directly proportional to the size of the generated particles, with average diameter of 21.4 nm and 5.8 nm for the 0.044 M and 0.022 M solutions, respectively. (C) 2012 Elsevier B.V. All rights reserved.