In this research work, coating of acrylic fibers (fibers spun from poly acrylonitrile) with copper sulfide was investigated. Surface of the acrylic fibers were coated with an insoluble conducting copper sulfide layer. One-step dipping method was carried out. Acrylic fibers were treated in a bath containing divalent copper ions, a reducing agent, which is capable of reducing the divalent copper ions to a monovalent copper ions and a sulfur-containing compound. This treatment resulted in a reduction of electrical resistance to 1 x 109 that of an almost infinite resistance for the untreated fibers. The influence of some parameters such as concentration of copper (II) sulfate, hydroxylamine sulfate, sodium thiosulfate, and temperature of treatment bath were also investigated. A second reduc ing material such as sodium dithionite was used to improve the electrical conductivity of the fibers. The amount of reacted copper was measured by atomic absorption technique. The surface properties of the coated-acrylic fibers were studied using scanning electron microscopy (SEM). Within the experimental conditions, a solution containing 1.2 g/dm(3) copper (II) sulfate, 1.6 g/dm(3) hydroxylamine sulfate, 3.6 g/dm(3) sodium thiosulfate, and 3 g/dm(3) sodium dithionite was selected as a suitable formulation. (c) 2007 Wiley Periodicals, Inc.