In this paper, in-situ electrospinning method was presented to directly fabricate semiconductor (Ag2S or Cu2S) nanostructures on the outer surfaces of polyacrylonitrile (PAN) nanofibers. PAN/metallic salt composite fibers were electrospun firstly as precursors, after UV irradiation photoreduction and the treatment of H2S gas, Ag2S or Cu2S nanostructures can be obtained on the outer surface of PAN nanofibers. The interactions between the polymer and metallic ions are believed to be the main factor in determining the position of metallic ions based on the electrospun nanofibers. Transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) are used to characterize the products. (c) 2006 Elsevier B.V. All rights reserved.